单选题Supposing 1 million leukemia cells were killed after 24 hours of exposure to radio waves, how many healthy cells would be killed under the same condition?A 1.2 million.B 1.4 million.C 0.8 million.D 2 million.

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What Is Cancer?

Cancer is actually a group of many related diseases that all have to do with cells.Cells
are the very small units that make up all________(1)things,including the human
body.There are billions of cells________(2)each person's body.
Cancer happens when cells that are not normal grow________(3)spread very
fast.Normal body cells grow and divide and know when to stop growing.Over time,they
also die._______(4)these normal cells,cancer cells just continue to grow and divide
out of control and don't die.Cancer cells usually group together to form tumors（肿瘤）.
A growing tumor becomes a lump of cancer cells_________(5)can destroy the
normal cells around the_________(6)and damage the body's healthy tissues.This
can make someone very _______(7).
Sometimes cancer cells break away from the original tumor and travel to other areas of
the________(8),where they keep growing and can go on to form new tumors.This
is how cancer__________(9).The spread of a tumor to a new place in the body is
__________(10)metastasis（转移）.
People with cancer may feel pretty sick at times一but can usually still do lots of
normal things._________(11)they are very sick,kids and teenagers with cancer
may still be able to go to school. They may be tired or bruise（出现青肿）easily, but they
__________( 1 2) sometimes go to camp , movies , and sleepover（在外过夜的）parties.
People with cancer still like the same things they did__________(13)they got sick.
Cancer in kids is rare一but today,many kids who do get cancer go on living normal
lives.The number of kids who beat cancer goes________(14)every year because of
new cancer treatments.So a lot of kids with cancer will some day drive cars,go to college,
have careers,and even get_________(15)and have families of their own.

_________(2)
A: by
B: in
C: with
D: at

Many Native Americans were killed during the ______ of the American West by Europeans in the 19th century.

A.shelter
B.construction
C.settlement
D.basement

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第三篇

Nuclear Power and Its Danger

Nqclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.
It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things
like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio
receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,
nuclear radiation is not harmless to human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital or-
gans.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely
safe.if the radiation does not hit anything important,the damage may not be significant. This is the case when only
a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones. But if the few
cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce them-
selves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.
This is another reason for some of the mystery about nuclear radiation.Serious damage can be done with-
out the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,
then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to
serious illness as result of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

Radiation can cause serious consequences even at the lowest level_________.
A:when it kills few cells
B:if it damages few cells
C:though the damaged cells can repair themselves
D:unless the damaged cells can reproduce themselves

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第一篇

Nuclear Power and Its Danger

Nuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.
This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

According to the passage,the danger of nuclear power lies in________.
A:nuclear mystery
B:radiation detection
C:nuclear radiation
D:radiation level

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第一篇

Human Heart can Make New Cells

Solving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues to
generate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows
with age.
The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart
diseases such as heart failure and heart attack,experts say.
"We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead
researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,
Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with
or whether they could be renewed,"he said.
"The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1
percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only
0.45 percent by age 75.
"If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially
possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for
example,a heart attack,"Frisen said.
That could lead to treatment that helps restore damaged hearts.
"A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the
Karolinska Institute."Chronic heart failure arises from heart cells dying," he said.
"With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal
ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells
make new and more cells to overcome the problem they are facing."
But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell
production to a rate that would replace cells faster than they are dying off,especially in older patients with
heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一
whether the rate of cell turnover in diseased hearts is the same remains unknown.

The human heart stops producing cardiac cells ______.
A:when a person becomes old
B:as soon as a person gets sick
C:immediately after a person is born
D:once a person dies

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第一篇

Human Heart can Make New Cells

Solving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues to
generate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows
with age.
The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart
diseases such as heart failure and heart attack,experts say.
"We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead
researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,
Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with
or whether they could be renewed,"he said.
"The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1
percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only
0.45 percent by age 75.
"If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially
possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for
example,a heart attack,"Frisen said.
That could lead to treatment that helps restore damaged hearts.
"A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the
Karolinska Institute."Chronic heart failure arises from heart cells dying," he said.
"With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal
ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells
make new and more cells to overcome the problem they are facing."
But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell
production to a rate that would replace cells faster than they are dying off,especially in older patients with
heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一
whether the rate of cell turnover in diseased hearts is the same remains unknown.

Chronic heart failure is attributed to _________.
A:the dying heart cells
B:the effect of pharmaceuticals
C:the weight of the patient
D:the life span of a person

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第二篇

Bone Marrow Transplantation

Bone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.
If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.
People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.
The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.
If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.
Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.
On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.

We can infer from this passage that_________.
A:bone marrow transplantation requires five procedures
B:bone marrow transplantation is complex
C:people with leukemia must need transplantation
D:people with cancer must donate bone marrow before treatment

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第一篇

Human Heart can Make New Cells

Solving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues to
generate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows
with age.
The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart
diseases such as heart failure and heart attack,experts say.
"We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead
researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,
Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with
or whether they could be renewed,"he said.
"The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1
percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only
0.45 percent by age 75.
"If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially
possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for
example,a heart attack,"Frisen said.
That could lead to treatment that helps restore damaged hearts.
"A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the
Karolinska Institute."Chronic heart failure arises from heart cells dying," he said.
"With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal
ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells
make new and more cells to overcome the problem they are facing."
But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell
production to a rate that would replace cells faster than they are dying off,especially in older patients with
heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一
whether the rate of cell turnover in diseased hearts is the same remains unknown.

It is not known yet if the rate of cell turnover in diseased hearts_________.
A:is high enough to replace cells faster than they're dying off
B:is of any use to researchers
C:is the same as that in healthy hearts
D:changes over time

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Just one hour's listening to an MP3 player can damage hearing,claim scientists.It causes temporary changes in hearing sensitivity which may lead to long-term harm,according to a new study.
The findings show over -stimulation of hair cells within the ear occurs even at varying volume levels for short periods of time.The study of almost 60 young people carried out by researchers at Ghent University,Belgium,is published in the Archives of Otolaryngology -Head&Neck Surgery journal.
It follows previous warnings from doctors that using MP3 players at high volumes with earphones that fit into the ear canal could lead to loss of hearing. In the latest study,21 people aged 19 to 28 years were exposed to pop and rock music using MP3 players at varying volumes for one hour. A second group of 28 men and women were a control group who were not exposed to MP3 music.
Hearing tests were carried out before and after the exposure,which found significant threshold or emission shifts were observed between almost every session of the noise exposure group compared with the control group.Lead researcher Hannah Kempler said:Excessive noise exposure can lead to metabolic and mechanical effects resulting in alterations of the structural elements of the inner ear that contains auditory sensory cells or"hair cells".
The European Commission has warned up to 10% of 30-year-old would have to wear a hearing device within the next decade because they listen to music too loudly through headphones.Surveys showed more than 90% of young people in Europe and the U.S.used MP3 players,often for several hours a day at maximum volume.Hearing experts recommend the 60/60 rule一listening to MP3 players for no more than 60 minutes at a time at 60% of maximum volume.Concern among EU health and safety officials has led to plan to ensure all MP3 players have the same maximum volume of 85 decibels(dB)一although users may be able to individually override it at their own risk.

Not much difference was found between the exposure group and the control group according to the hearing tests after the exposure.
A:Right
B:Wrong
C:Not mentioned

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Leukemia

Leukemia is the most common type of cancer kids get,but it is still very rare.Leukemia involves the
blood and blood-forming organs,such as the bone marrow.________(46)
A kid with leukemia produces lots of abnormal white blood cells in the bone marrow. Usually,white
blood cells fight infection,but the white blood cells in a person with leukemia don't work the way they're
supposed to.________(47)The abnormal white blood cells multiply out of control,filling the bone marrow
and making it hard for enough normal,infection-fighting white blood cells to form.Other blood cells一such as
red blood cells(that carry oxygen in the blood to the body's tissues)and platelets(that allow blood to
clot）一are also crowded out by the white blood cells of leukemia. These cancer cells may also move to other
parts of the body,including the bloodstream,where they continue to multiply and build up.
Although leukemia can make kids sick,most of the time it is treatable,and kids get better. Almost all
leukemia patients are treated with chemotherapy,which means using anti-cancer drug.
________(48)Chemotherapy quickly goes to work,traveling through the blood to the bone marrow.
There,the drugs can attack the cancer cells.After several weeks of chemotherapy,many kids begin to feel
better.
Some children with leukemia will also have to have radiation therapy,too.________(49)If the cancer
isn't getting better from using the usual amounts of chemotherapy and radiation,then a kid with leukemia
will probably need more treatment一with higher doses of chemotherapy and radiation to finally kill the cancer
cells.But this heavy-duty treatment will also harm the normal cells in the kid's bone marrow too,and the
bone marrow will no longer be able to produce normal blood cells.So,doctors will then give a kid一or anyone
else with bone marrow that is no longer working一normal bone marrow tissue from someone else who is
healthy.________(50)

___________（50）
A:The chemotherapy drugs are given through a catheter,a narrow tube that is inserted into a blood vessel, sometimes in the kid's upper chest.
B:Early symptoms of leukemia are often overlooked,since they may resemble symptoms of the flu or other common diseases.
C:This is a special procedure called a bone marrow transplant,and it helps the patient make new blood cells so they can recover from the leukemia.
D:Bone marrow is the innermost part of some bones where blood cells are first made.
E:They don't protect the person from infections very well.
F: Radiation therapy uses invisible high-energy waves(similar to X-rays)to kill cancerous cells.

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Nuclear Power and Its Danger
Nuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.
lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.
This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

The underlined word"significant"in Paragraph 3 most probably means______.
A:fatal
B:meaningful
C:remarkable
D:harmful

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第一篇

Nuclear Power and Its Danger

Nuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.
This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

Radiation can hurt us in the way that it can________.
A:kill large numbers of cells in main organs so as to cause death immediately
B:damage cells which may grow into cancer years later
C:affect the healthy growth of our offspring
D:all of the above

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Nuclear Power and Its Danger
Nuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.
lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.
This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

Radiation1 can cause serious consequences even at the lowest level______.
A:when it kills few cells
B:if it damages few cells
C:though the damaged cells can repair themselves
D:unless the damaged cells can reproduce themselves

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第二篇

Bone Marrow Transplantation

Bone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.
If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.
People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.
The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.
If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.
Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.
On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.

Before receiving healthy cells,diseased cells must_________.
A:undergo chemotherapy
B:go through radiation
C:be prepared
D:be wrecked

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第二篇

Bone Marrow Transplantation

Bone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.
If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.
People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.
The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.
If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.
Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.
On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.

Healthy stem cells may come from the following sources EXCEPT__________.
A:peripheral blood stem cells
B:baby blood
C:bone marrow
D:cord blood

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第二篇

Bone Marrow Transplantation

Bone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.
If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.
People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.
The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.
If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.
Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.
On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.

The new marrow usually comes from__________.
A:people with cancer
B:a family member
C:an organ donor
D:a relative or a stranger

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第二篇

Bone Marrow Transplantation

Bone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.
If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.
People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.
The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.
If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.
Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.
On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.

The word"immature"in paragraph 1 means___________.
A:major
B:outstanding
C:underdeveloped
D:significant

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第二篇

Nuclear Power and Its Danger

Nuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.
Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.
It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things
like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio
receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,
nuclear radiation is not harmless to'human beings and other living things.
At very high levels,radiation can kill an animal or human being outright by killing masses of cells in
vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is
comnpletely safe.If the radiation does not hit anything important,the damage may not be significant.This is
the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells
with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in
trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not
show up for many years.
There is another reason for the mystery of nuclear radiation.Serious damage can be done without the
victim being aware at the time that damage occurs. A person can be irradiated and feel fine,then die of cancer
five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result
of radiation absorbed by its grandparents.
Radiation can hurt us.We must know the truth.

Radiation can cause serious consequences even at the lowest level_______________.
A:when it kills a few cells
B:if it damages a few cells
C:though the damaged cells can repair themselves
D:unless the damaged cells can reproduce themselves