The brain finds it best to keep smell receptors（ ）for unfamiliar and emergency signals such as the smell of smoke,which might indicate the danger of fire.A.available B.reliable C.identifiable D.suitable

请阅读Passage l。完成第21—25小题。
Passage 1
It's one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse s brain.
But now Wendy Ingram, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to"cure" mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause different diseases among humans, especially pregnant women--it is linked to blindness and the death of unborn babies.
However, the parasite's effects on mice are unique. Ingram and her team measured how mice reacted to a cat's urine(尿) before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely around the test area.
But that's not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection. They no longer reacted with fear to a cat's smell,which could indicate that the infection has caused a permanent change in mice's brains.
Why does a parasite change a mouse's brain instead of making it sick like it does to humans?
The answer lies in evolution.
"It's exciting scary to know how a parasite can manipulate a mouse's brain this way," Ingram said. But she also finds it inspiring."Typically if you have a bacterial infection, you go to a doctor and take antibiotics and the infection is cleared and you expect all the symptoms to also go away."
She said, but this study has proven that wrong."This may have huge implications for infectious disease medicine."

Which of the following statements is true according to the passage?
查看材料

A．Toxoplasma gondii causes people strange and deadly diseases.
B．With certain infection the infectious disease cannot be cured completely.
C．Human beings infected by toxoplasma gondii will have permanent brain damage.
D．Toxoplasma gondii is harmful to human beings, but it does no harm to mice.

Primer on Smell
In addition to bringing out1 the flavor of food, what does the sense of smell do for us ?
Smell “gives us information about place, about where we are,” says Randall Reed, a Johns Hopkins University professor whose specialty is the sense of smell. ___1___ “Whether we realize it or not, we collect a lot of information about who is around us based on smell,” says Reed.
Even at a distance, odors can warn us of2 trouble — spoiled food, leaking gas, or fire. “It’s a great alert,” offers Donald Leopold, a doctor at Johns Hopkins. For example, if something in the oven is burning, everyone in the house knows it.
With just a simple scent, smell can also evoke very intense emotion. Let’s say, for example, that the smell is purple petunias. ___2___ Now let’s imagine that your mother died when you were three, and she used to have a flower garden. You wouldn’t need to identify the smell or to have conscious memories of your mother or her garden. You would feel sad as soon as you smelled that spicy odor.
Compared with3 animals, how well do people detect smelts ?
That depends on what you mean by “how well”. We are low on receptor cells ： current estimates say that humans have roughly five million smell-receptor cells, about as many as a mouse. ___3___
Reed says that, across species, there is a relatively good correlation between the number of receptor cells and how strong the sense of smell is. “You can hardly find the olfactory bulb in a human brain —— it’s a pea-sized object. In a mouse, it’s a little bigger. It’s bean-sized in a rat, about the size of your little finger in a rabbit, and the size of your thumb in a bloodhound.”
Does that mean that our sense of smell is not very acute ?
Not exactly. While we may not have the olfactory range of other creatures, the receptors we do have are as sensitive as those of any animal. ___4___ A trained “nose”, such as that of a professional in the perfume business, can name and distinguish about 10,000 odors. Reed says that a perfume expert can sniff a modem scent that has a hundred different odorants in it, go into the lab, and list the ingredients. “In a modest amount of time, he comes back with what to you or me would smell like a perfect imitation of that perfume. It’s amazing.”
What happens to4 our sense of smell as we age ?
Many people continue to have good olfactory function as they get older. ___5___ Leopold says that smell is generally highest in childhood, stays the same from the teens through the 50s, and drops starting at about 60 for women and 65 for men. “The average 80-year-old is only able to smell things half as well as the average 20-year-old,” says Leopold.

词汇：
scent /sent/ n. 气味，香味
petunia /p 'tju:ni / n. 喇叭花
olfactory / l'f kt( )ri/ adj. 嗔觉的，味道的
sniff /snif/ v. 嗅，闻，用力吸

注释：
1. bring out：使……显出，使……变得明显
2. warn of：发出关于……的警告。warn sb. of sth.：警告某人某事
3. compare with：与……相比
4. happen to：发生于，发生在

练习：
A These flowers have a rich spiciness that no other petunia has.
B Odors, or smells, can warn us about trouble.
C That’s not the rule, however.
D And smell tells us about people.
E We can also think, and we make conscious (and successful) efforts to tell the difference between one smell and another.
F A rat has some 10 million, a rabbit 20 million, and a bloodhound 100 million.

共用题干
第一篇

The Smell of Money

For many years large supermarkets have been encouraging us to spend money by pumping the smell of
freshly-baked bread into their stores. Now Dale Air, a leading firm of aroma（香气）consultants, has been
approached by Barclay's Bank to develop suitable artificial smells for their banks.Researchers have suggested
that surrounding customers with the"smell of money"will encourage them to feel relaxed and optimistic and
give them added confidence in the bank's security and professionalism.
But before a smell can be manufactured and introduced into banks' air conditioning systems,it must be
identified and chemically analyzed,and this has proved to be difficult.The problem is that banknotes and
coins tend to pick up the smell of their surroundings.So cash that has been sitting in a cash register at a
fishmonger's（鱼贩）will smell of fish,and banknotes used to pay for meals in restaurants will tend to smell
of food.
It may be a challenge,but aroma experts have little doubt that the use of artificial smells can be an effective
form of subconscious advertising. Lunn Poly,a British travel company,introduced the smell of coconuts（椰
子）into its travel agencies and saw a big increase in spending by holiday makers.Many cafs now have elec-
tric dispensers（自动售货机）that release the smell of freshly roasted coffee near their entrances, subtly
encouraging customers to come in and have a drink or snack. Even prestigious car maker Rolls-Royce has
been spraying the inside of its cars to enhance the smell of the leather seats.
"The sense of smell is probably the most basic and primitive of all human senses,"explains researcher
Jim O'Riordan. "There is a direct pathway from the olfactory（嗅觉的）organs in the nose to the brain."It
is certainly true that most people find certain smells incredibly strong,stirring memories and feelings in a way
that few other stimulants（刺激物）can rival. It is a phenomenon marketing consultants have long recog-
nized,but until recently have been unable to harness."We've made great progress but the technology of
odour production is still in its infancy,"says O'Riordan."Who knows where it will take us."

Researchers believe that introducing the"smell of money"into banks will encourage people_________.
A:to spend money
B:to feel confident about banks
C:to earn more money
D:to withdraw money from banks

It’s one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse’ s brain.
But now Wendy Ingram, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to “cure” mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause different diseases among humans, especially pregnant women—it is linked to blindness and the death of unborn babies.
However, the parasite’s effects on mice are unique. Ingram and her team measured how mice reacted to a cat's urine (尿) before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely around the test area.
But that's not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection. They no longer reacted with fear to a cat's smell, which could indicate that the infection has caused a permanent change in mice's brains.
Why does a parasite change a mouse's brain instead of making it sick like it does to humans The answer lies in evolution.
“It’s exciting scary to know how a parasite can manipulate a mouse's brain this way,"Ingram said. But she also finds it inspiring. "Typically if you have a bacterial infection, you go to a doctor and take antibiotics and the infection is cleared and you expect all the symptoms to also go away,” she said, but this study has proven that wrong. “This may have huge implications for infectious disease medicine."

Which of the following statements is true according to the passage 查看材料

A.Toxoplasma gondii causes people strange and deadly diseases.
B.With certain infection the infectious disease cannot be cured completely.
C.Human beings infected by toxoplasma gondii will have permanent brain damage.
D.Toxoplasma gondii is harmful to human beings, but it does no harm to mice.

请阅读Passage l。完成第21—25小题。
Passage 1
It's one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse s brain.
But now Wendy Ingram, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to"cure" mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause different diseases among humans, especially pregnant women--it is linked to blindness and the death of unborn babies.
However, the parasite's effects on mice are unique. Ingram and her team measured how mice reacted to a cat's urine(尿) before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely around the test area.
But that's not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection. They no longer reacted with fear to a cat's smell,which could indicate that the infection has caused a permanent change in mice's brains.
Why does a parasite change a mouse's brain instead of making it sick like it does to humans?
The answer lies in evolution.
"It's exciting scary to know how a parasite can manipulate a mouse's brain this way," Ingram said. But she also finds it inspiring."Typically if you have a bacterial infection, you go to a doctor and take antibiotics and the infection is cleared and you expect all the symptoms to also go away."
She said, but this study has proven that wrong."This may have huge implications for infectious disease medicine."

The passage is mainly about__________.
查看材料

A．mice' s inborn terror of cats
B．the evolution of Toxoplasma
C．a new study about the effects of a parasite on mice
D．a harmful parasite called Toxoplasma gondii

Which of the following is a slip of tongue

A.No cross, no crown．
B.No pains, no gains．
C.No sweat without sweet．
D.No smoke without fire．

This may be because some people do not have the genes necessary to generate particular smell receptors in the nose.These receptors are the cells which sense smells and send（ ）to the brain.

A.signs
B.stimuli
C.messages
D.impulses

共用题干
第一篇

The Smell of Money

For many years large supermarkets have been encouraging us to spend money by pumping the smell of
freshly-baked bread into their stores. Now Dale Air, a leading firm of aroma（香气）consultants, has been
approached by Barclay's Bank to develop suitable artificial smells for their banks.Researchers have suggested
that surrounding customers with the"smell of money"will encourage them to feel relaxed and optimistic and
give them added confidence in the bank's security and professionalism.
But before a smell can be manufactured and introduced into banks' air conditioning systems,it must be
identified and chemically analyzed,and this has proved to be difficult.The problem is that banknotes and
coins tend to pick up the smell of their surroundings.So cash that has been sitting in a cash register at a
fishmonger's（鱼贩）will smell of fish,and banknotes used to pay for meals in restaurants will tend to smell
of food.
It may be a challenge,but aroma experts have little doubt that the use of artificial smells can be an effective
form of subconscious advertising. Lunn Poly,a British travel company,introduced the smell of coconuts（椰
子）into its travel agencies and saw a big increase in spending by holiday makers.Many cafs now have elec-
tric dispensers（自动售货机）that release the smell of freshly roasted coffee near their entrances, subtly
encouraging customers to come in and have a drink or snack. Even prestigious car maker Rolls-Royce has
been spraying the inside of its cars to enhance the smell of the leather seats.
"The sense of smell is probably the most basic and primitive of all human senses,"explains researcher
Jim O'Riordan. "There is a direct pathway from the olfactory（嗅觉的）organs in the nose to the brain."It
is certainly true that most people find certain smells incredibly strong,stirring memories and feelings in a way
that few other stimulants（刺激物）can rival. It is a phenomenon marketing consultants have long recog-
nized,but until recently have been unable to harness."We've made great progress but the technology of
odour production is still in its infancy,"says O'Riordan."Who knows where it will take us."

Researchers think__________.
A:artificial smells help to improve people's memory
B:the technology to produce artificial smells is in the early stage
C:artificial smells are harmful
D:the production of artificial smells is profitable

It’s one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse’ s brain.
But now Wendy Ingram, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to “cure” mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause different diseases among humans, especially pregnant women—it is linked to blindness and the death of unborn babies.
However, the parasite’s effects on mice are unique. Ingram and her team measured how mice reacted to a cat's urine (尿) before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely around the test area.
But that's not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection. They no longer reacted with fear to a cat's smell, which could indicate that the infection has caused a permanent change in mice's brains.
Why does a parasite change a mouse's brain instead of making it sick like it does to humans The answer lies in evolution.
“It’s exciting scary to know how a parasite can manipulate a mouse's brain this way,"Ingram said. But she also finds it inspiring. "Typically if you have a bacterial infection, you go to a doctor and take antibiotics and the infection is cleared and you expect all the symptoms to also go away,” she said, but this study has proven that wrong. “This may have huge implications for infectious disease medicine."

The author's attitude towards the experiment is__________.查看材料

A.positive
B.subjective
C.negative
D.objective