单选题A pharmaceutical company tested a new painkiller on 1,000 lab rats that were fed large doses of the painkiller for a two-month period. By the end of the experiment, 39 of the rats had died. The company concluded that the painkiller was sufficiently saf

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第二篇

Exercise and Brain

Just as exercise strengthens the heart and lungs,bones and muscles,it may also power up the brain.A succession of scientific studies of animals implies that physical activity has a positive effect on mental functioning.
"It's clear that the brain benefits from exercise,"says brain scientist William Greenough of the University of Illinois at Urbana-Champaign.His studies with rats have demonstrated two primary effects of activity:Vigorous physical exercise provides the brain with more fuel,and skill-based ex-ercise increases the formation of connections in the brain, which, according to the proposals of some scientists,may make the brain better able to process information.
In one experiment,laboratory rats were separated into three groups.One group was exercised by running inside an automatic wheel,a second group improved their skills in a complicated obstacle course,and a third group was inactive.
"The animals that learned to go through the obstacle course exhibited a greater number of brain connections than the animals in the exercised or inactive groups,"Greenough said."In contrast, the animals that exercised inside the automatic wheel possessed a greater density of blood vessels in the brain than did either of the other two groups of animals."
Learning a new dance step may boost the brain in the same way that learning a language can, he says.And if the dance is a good physical exercise as well,the benefits multiply.Young brains may be especially able to boost brain power through exercise,suggested another of Greenough's experiments that showed the most significant changes in the brain occurred among rats that had been exercised when very young.And while animals aren't people,he says it is logical to make the inference that an effect found in rats may also apply to humans.
Human studies have focused primarily on older adults and suggest that regular exercise can improve the speed with which the brain processes information.Measurements made by Arthur Kramer at the University of Illinois demonstrated that inactive adults,aged 63 to 82,could hit buttons faster in response to a tone after they went through a 10-week water exercise course.A corresponding control group that didn't exercise showed no improvement.

Which statement is correct according to the passage?
A:The effect of exercises found in rats can not apply to people.
B:Changes in the brain occurred among young rats are more significant than those among adult rats.
C:Regular exercise can only improve the speed with which the older adults' brain processes information.
D:The author encourages people do more skill-based exercise instead of vigorous physical exercise.

Rats and other animals need to be highly at tuned to social signals from others so that can identify friends to cooperate with and enemies to avoid.To find out if this extends to non-living beings,Loleh Quinn at the University of California,San Diego,and her colleagues tested whether rats can detect social signals form robotic rats.They housed eight adult rats with two types of robotic rat-one social and one asocial一for 5 our days.The robots rats were quite minimalist,resembling a chunkier version of a computer mouse with wheels-to move around and colorful markings.During the experiment,the social robot rat followed the living rats around,played with the same toys,and opened caged doors to let trapped rats escape.Meanwhile,the asocial robot simply moved forwards and backwards and side to side Next,the researchers trapped the robots in cages and gave the rats the opportunity to release them by pressing a lever.Across 18 trials each,the living rats were 52 percent more likely on average to set the social robot free than the asocial one.This suggests that the rats perceived the social robot as a genuine social being.They may have bonded more with the social robot because it displayed behaviours like communal exploring and playing.This could lead to the rats better remembering having freed it earlier,and wanting the robot to return the favour when they get trapped,says Quinn.The readiness of the rats to befriend the social robot was surprising given its minimal design.The robot was the same size as a regular rat but resembled a simple plastic box on wheels.“We'd assumed we'd have to give it a moving head and tail,facial features,and put a scene on it to make it smell like a real rat,but that wasn’t necessary,”says Janet Wiles at the University of Queensland in Australia,who helped with the research.The finding shows how sensitive rats are to social cues,even when they come from basic robots.Similarly,children tend to treat robots as if they are fellow beings,even when they display only simple social signals.“We humans seem to be fascinated by robots,and it turns out other animals are too,”says Wiles.
What did the social robot do during the experiment?

A.It followed the social robot.
B.It played with some toys.
C.It set the trapped rats free.
D.It moved around alone.

Rats and other animals need to be highly at tuned to social signals from others so that can identify friends to cooperate with and enemies to avoid.To find out if this extends to non-living beings,Loleh Quinn at the University of California,San Diego,and her colleagues tested whether rats can detect social signals form robotic rats.They housed eight adult rats with two types of robotic rat-one social and one asocial一for 5 our days.The robots rats were quite minimalist,resembling a chunkier version of a computer mouse with wheels-to move around and colorful markings.During the experiment,the social robot rat followed the living rats around,played with the same toys,and opened caged doors to let trapped rats escape.Meanwhile,the asocial robot simply moved forwards and backwards and side to side Next,the researchers trapped the robots in cages and gave the rats the opportunity to release them by pressing a lever.Across 18 trials each,the living rats were 52 percent more likely on average to set the social robot free than the asocial one.This suggests that the rats perceived the social robot as a genuine social being.They may have bonded more with the social robot because it displayed behaviours like communal exploring and playing.This could lead to the rats better remembering having freed it earlier,and wanting the robot to return the favour when they get trapped,says Quinn.The readiness of the rats to befriend the social robot was surprising given its minimal design.The robot was the same size as a regular rat but resembled a simple plastic box on wheels.“We'd assumed we'd have to give it a moving head and tail,facial features,and put a scene on it to make it smell like a real rat,but that wasn’t necessary,”says Janet Wiles at the University of Queensland in Australia,who helped with the research.The finding shows how sensitive rats are to social cues,even when they come from basic robots.Similarly,children tend to treat robots as if they are fellow beings,even when they display only simple social signals.“We humans seem to be fascinated by robots,and it turns out other animals are too,”says Wiles.
It can be learned from the text that rats________

A.appear to be adaptable to new surroundings
B.are more socially active than other animals
C.behave differently from children in socializing
D.are more sensitive to social cues than expected

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New Product Will Save lives

Drinking water that looks clean may still contain bugs（虫子）,which can cause illness.
A small company called Genera Technologies has produced a testing method in three
stages,which shows whether water is safe.The new test shows if water needs chemicals
added to it,to destroy anything harmful.It was invented by scientist Dr. Adrian Parton,
who started Genera five years ago.He and his employees have developed the test together
with a British water company.
Andy Headland,Genera's marketing director,recently presented the test at a
conference in the USA and forecast good American sales for it.Genera has already sold 11
of its tests at$42,500 a time in the UK and has a further four on order. It expects to sell
another 25 tests before the end of March.The company says it is the only test in the UK to
be approved by the government.
Genera was formed five years ago and until October last year had only five employees;
it now employs 14.Mr Headland believes that the company should make around$19 million
by the end of the year in the UK alone.

Before he set up Genera,Dr. Parton had worked for a British water company.
A:Right
B:Wrong
C:Not mentioned

The author easily built a team of his company because __________.

A.they were underpaid at their previous jobs
B.they were turned down by other companies
C.they were confident of the author and his business
D.they were satisfied with the salaries in his company

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第三篇

Sugar Accelerate the Process of Aging

Sugar is widely used in our daily life to make food and drinks sweet,though too much intake of it may lead to diabetes.However,today's study found it also makes people get old faster. Rats that eat high levels of a natural sugar known as fructose seem to age faster than other rats.And the same could be true for people who eat too much sweet junk food,said Israeli researchers.
Fructose,a substance found naturally in honey and fruit,is used widely in foods ranging from soft drinks to yogurt. But while its sweet taste is popular,the sugar could cause wrinkles and health problems,the researchers said.Dr. Moshe Werman and Boaz Levi of the Technion-Israel Institute of Technology fed large amounts of fructose to laboratory rats.Writing in the Journal of Nutrition,they said the fructose-fed rats showed changes in the collagen of their skin and bones.
Collagen,a fibrous protein found in connective tissue,bone and cartilage,basically holds the body together. The loss of collagen is what causes sagging and deep wrinkles in older people.
The process affected,Werman's team said,is known as"cross linking"."Too much crosslinking reduces elasticity and makes the skin stiff and rigid,and these are the conditions that encourage wrinkled skin,"Werman said in a statement. He said the same could be true of people, although this has not been shown."Americans are eating more and more processed foods such as carbonated drinks,baked goods,canned fruits,jams and dairy products that contain fructose," Werman said.Other studies have shown that high fructose intake can affect how the body handles glucose and increases insulin resistance一which can both be important measures of the tendency toward diabetes.
The rats Werman worked with were fed much more than the average adult person might eat in a day,which is standard in such experiments.The rats were 12.5 grams of fructose per kg(2.2 pounds)of weight every day for a year. To compare,a person weighing 154 pounds(70kg)who drinks a quart(liter)of cola consumes about 60 grams of fructose,or 0.8 grams per kg of body weight.

According to the passage,people who eat too much sweet junk food will_______.
A:slow down their process of aging
B:more likely to get diabetes
C:get heavier than others
D:age faster than average people

Rats and other animals need to be highly at tuned to social signals from others so that can identify friends to cooperate with and enemies to avoid.To find out if this extends to non-living beings,Loleh Quinn at the University of California,San Diego,and her colleagues tested whether rats can detect social signals form robotic rats.They housed eight adult rats with two types of robotic rat-one social and one asocial一for 5 our days.The robots rats were quite minimalist,resembling a chunkier version of a computer mouse with wheels-to move around and colorful markings.During the experiment,the social robot rat followed the living rats around,played with the same toys,and opened caged doors to let trapped rats escape.Meanwhile,the asocial robot simply moved forwards and backwards and side to side Next,the researchers trapped the robots in cages and gave the rats the opportunity to release them by pressing a lever.Across 18 trials each,the living rats were 52 percent more likely on average to set the social robot free than the asocial one.This suggests that the rats perceived the social robot as a genuine social being.They may have bonded more with the social robot because it displayed behaviours like communal exploring and playing.This could lead to the rats better remembering having freed it earlier,and wanting the robot to return the favour when they get trapped,says Quinn.The readiness of the rats to befriend the social robot was surprising given its minimal design.The robot was the same size as a regular rat but resembled a simple plastic box on wheels.“We'd assumed we'd have to give it a moving head and tail,facial features,and put a scene on it to make it smell like a real rat,but that wasn’t necessary,”says Janet Wiles at the University of Queensland in Australia,who helped with the research.The finding shows how sensitive rats are to social cues,even when they come from basic robots.Similarly,children tend to treat robots as if they are fellow beings,even when they display only simple social signals.“We humans seem to be fascinated by robots,and it turns out other animals are too,”says Wiles.James Wiles notes that rats________

A.can remember other rat's facial features
B.differentiate smells better than sizes
C.respond more to cations than to looks
D.can be scared by a plastic box on wheels

Rats and other animals need to be highly at tuned to social signals from others so that can identify friends to cooperate with and enemies to avoid.To find out if this extends to non-living beings,Loleh Quinn at the University of California,San Diego,and her colleagues tested whether rats can detect social signals form robotic rats.They housed eight adult rats with two types of robotic rat-one social and one asocial一for 5 our days.The robots rats were quite minimalist,resembling a chunkier version of a computer mouse with wheels-to move around and colorful markings.During the experiment,the social robot rat followed the living rats around,played with the same toys,and opened caged doors to let trapped rats escape.Meanwhile,the asocial robot simply moved forwards and backwards and side to side Next,the researchers trapped the robots in cages and gave the rats the opportunity to release them by pressing a lever.Across 18 trials each,the living rats were 52 percent more likely on average to set the social robot free than the asocial one.This suggests that the rats perceived the social robot as a genuine social being.They may have bonded more with the social robot because it displayed behaviours like communal exploring and playing.This could lead to the rats better remembering having freed it earlier,and wanting the robot to return the favour when they get trapped,says Quinn.The readiness of the rats to befriend the social robot was surprising given its minimal design.The robot was the same size as a regular rat but resembled a simple plastic box on wheels.“We'd assumed we'd have to give it a moving head and tail,facial features,and put a scene on it to make it smell like a real rat,but that wasn’t necessary,”says Janet Wiles at the University of Queensland in Australia,who helped with the research.The finding shows how sensitive rats are to social cues,even when they come from basic robots.Similarly,children tend to treat robots as if they are fellow beings,even when they display only simple social signals.“We humans seem to be fascinated by robots,and it turns out other animals are too,”says Wiles.Quin and her colleagues conducted a test to see if rats can________

A.pickup social signals from non-living rats
B.distinguish a friendly rat from a hostile one
C.attain sociable traits through special training
D.send out warning messages to their fellow

The company had about 20 notebook computers,but only one-third__________used regularly.

A.is
B.are
C.was
D.were