Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the color of a dark-striped zebrafish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebrafish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

1. The passage mainly tells us that ________.

2. It can be inferred from the passage that ________.

3.Scientists have done an experiment on a dark-striped zebrafish in order to ________.

4.The reason why Europeans are light-skinned is probably that _____

5.The writer’s attitude towards the discovery is ________.

This is a dangerous world we live in. The number of murders goes up every year, people are dying of cancer, more people contract HIV, more teens are using drugs, ect. You know this because you’ve heard all the statistics on the news and in the paper. But do you really have an accurate idea what they mean? The numbers are going up, but how do they compare to the growth in population? Are more cases of these diseases being reported because of better testing techniques, or are the diseases more common? The fact is that without knowing the background statistics mean very little.

This growing trend of reporting only part of the information is becoming dangerous. For example, several years ago a high school student reported the dangers of the chemical known as dihydrogen monoxide. This chemical, found in most cancerous tumors, is often found in the blood of people drunk on alcohol, and causes complete physical and mental dependence for those who take the chemical even once. After reading his report, more than 75% of his Advanced Placement Chemistry class voted to forbid this dangerous chemical! Every one of the above statement is true, yet this chemical is necessary to all life on earth. The students made a mistake because they voted knowing only a few statements and statistics, rather than the chemical’s full background.

The point of this article is that one should be aware of what is and is not being said. When one finds a new fact or number, one should try to consider other important information before forming an opinion with only half-truths. Always remember that the author is trying to convince you of his or her own view, and will leave our information that is different from his view. For example, look again at the statistics that suggest skiing is safe. Only 32 people die each year when skiing, while 897 die from lightening strikes, but which is really more dangerous? If you think more about it, you will realize far fewer people go skiing each year than the number of people in danger of a lightning strike. When you think about it again, skiing is more dangerous than you might at first think when looking at the statistics. If we teenagers are to be left in this world, we had better be able to think critically, and form our own views, rather than be easily persuaded by another’s. To be warned is just to be prepared.

1.What’s the author’s attitude towards the growing trend of reporting only part of the      

  information?

Disapproving   B. Positive       C. Indifferent     D. Dangerous

2.In the first paragraph, what does the writer suggest?

A. We are now living in a dangerous world.

B. We get a lot of false statistics from the media.

C. There are around us more and more murders diseases, ect.

D. Statistics alone without full background don’t give us an accurate picture of things.

3.What’s the purpose of the writer’s using the two examples in the second paragraph?

A. To argue that high school students are easily persuaded.

B. To prove what is necessary to us might be dangerous.

C. To show the danger of reporting only part of the information.

D. To warn us of the harmful substance around us.

4.Relative information is often left out because ___________________. 

A. it is not important

B. the author is trying to show what he or she says is true

C. readers will consider other important information

D. readers are able to form an opinion with half-truths

5.What can we learn from the passage?

A. Some measures must be taken to protect our dangerous world.

B. The growing trend of reporting only half-truths is getting out of control.

C. Teenagers ought to improve their ability of telling right from wrong.

D. We should learn to think critically and look at problems from all sides.

When an ant dies, other ants take it out of the nest, often within an hour after its death. This behavior interests scientists and they wonder how ants know for sure—and so soon—that another ant is dead.

One scientist recently came up with a way to explain this ant behaviour. Dong-Hwan Choe is a biologist, a scientist who studies animals and plants. He found that ants have a chemical on the outside of their bodies that signals to other ants, “I'm dead—take me away” when it is dead.

But there's a question to answer: As we know, if an ant is dead, it stops moving. But when an ant is sleeping or knocked unconscious, it is also not moving. However, other ants don't move the living ant out of the nest. How do they know this ant is not dead? Choe found that ants have another chemical on their bodies, which tells nearby ants something like, “Wait—I'm not dead yet” when it is not dead. Choe suspects that when an ant dies, the chemical that says, “Wait I'm not dead yet” quickly goes away. When other ants detect the “dead” chemical without the “not dead yet” chemical, they move away the body.

To test his theory , Choe and his team put different chemicals on ants. When the scientists used the “I'm dead” chemical, other ants quickly moved the treated ant away. When the scientists used the “Wait—I'm not dead yet” chemical, other ants left the treated ant alone. Choe believes this behavior shows that the “not dead yet” chemical overrides the “dead” chemical when picked up by other ants. And that when an ant dies, the “not dead yet” chemical fades away. Other nearby ants then detect the remaining “dead” chemical and remove the body from the nest.

Understanding this behavior can help scientists figure out how to stop ants from invading new places and causing problems.

1.What is the function of the first paragraph?

A. Leading the following paragraphs.

B. Showing the main idea of the passage.

C. Introducing the background of the passage.

D. Giving a summary of the passage.

2.Which of the following has the closest meaning to the underlined word “overrides” in the fourth paragraph?

A. is weaker than        B. is stronger than

C. is better than    D. is worse than

3.What can we learn from the passage?

A. Living ants can also be taken away when they are not moving.

B. When an ant dies, it can tell others using a certain chemical.

C. A living ant can pretend to be dead using a special chemical.

D. Ants often use chemicals to communicate with each other.

4.Which of the following descriptions about Dong-Hwan Choe is right?

A. Choe did this study in order to stop ants from invading new places.

B. Choe is a biologist who is only interested in animals, especially in ants.

C. Choe first came up with an idea to explain this ant behavior，and then did some tests to prove his theory.

D. Choe did the research on this ant behavior on his own

Despite their______ of interest，Fleming kept trying to develop the chemical ______ it would be safe and effective.

A．lacking；in order toB．lack；so thatC．lack；so as to D．lacking；so that

It is thought that crying is hardly an activity encouraged by society. Tear, whether they are of sorrow, anger, or joy, typically make Americans feel uncomfortable and embarrassed. The shedder of tears (落泪者) is likely to apologize, even when a great tragedy was the cause. The observer of tears is likely to do everything possible to put an end to the emotional tears. But judging from recent studies of crying behavior, both those responses to tears are often inappropriate and may even be counterproductive (适得其反).

Humans are the only animals clearly known to shed emotional tears. Since evolution has given rise to few purposeless physiological responses, it is logical to assume that crying has one or more functions that enhance (increase) survival.

Although some observers have suggested that crying is a way to ask for assistance form others (as a crying baby might from its mother), the shedding of tears is hardly necessary to get help. Vocal cries would have been quite enough, more likely than tears to gain attention. So, it appears, there must be something special about tears themselves.

Indeed, the new studies suggest that emotional tears may play a direct role in alleviating stress, University of Minnesota researchers who are studying the chemical composition of tears have recently isolated two important chemicals from emotional tears. Both chemicals are found only in tears that are shed in response to emotion. Tears shed because of exposure to cut onion would contain no such substance.

Other researchers are investigating the usefulness of tears as a means of diagnosing human ills and monitoring drugs. At Tulane University’s Teat Analysis Laboratory Dr. Peter Kastl and his colleagues report that they can use tears to detect drug abuse, to study the causes of “dry eye” syndrome（综合症）and the effects of eye surgery, and perhaps even to measure exposure to environmental pollutants.

What does the phrase “both those responses” in Paragraph 1 refer to ?

       A．Crying out of sorrow and shedding tears for happiness.

       B．The embarrassment and unpleasant sensation of the observers.

       C．The tear shedder’s apology and the observer’s effort to stop the crying.

       D．Linking illness with crying and finding the chemical composition of tears.

From the passage we can infer that        .

       A．it is unnatural for people to shed tears

       B．we can reduce our stress by shedding tears

       C．shedders of tears can’t get help by crying loudly

       D．unlike animals, humans can shed tears for survival

What does the passage mainly talk about?

       A．Roles of emotional tears. B．functions of shedding tears.

       C．Unwelcome shedders of tears. D．Research on the effects of tears.