She _______ the film. She knows nothing about it.
A. can’t see B. can’t have seen C. must see D. mustn’t have seen
— Could I use your dictionary?
— Sure you ______. _______.
A. can; Go ahead B. can; Use it C. could; Help yourself D. could; Take it
Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour.
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 colour of a dark-striped zebrafish to uniform gold by inserting a version of the pigment(色素) gene into a young fish. As with humans, zebrafish skin colour is determined by pigment cells, which contain melanosomes(黑色素). The number, size and darkness of melanosomes per pigment cell determines skin colour.
It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation(变异) in the gene for melanosome production. This results in less pigmented skin.
However, Keith Cheng, leader of the research team, points out that the mutation is dif ferent 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 vit amin D. So the related gene changes, according to Cheng.
Asians have the same version of the gene as Africans, so they pr obably acquired their light skin through the action of some other gene that affects skin colour, said Cheng.
The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment did on Michael Jackson.
1.. The passage mainly tells us that ________.
A. people can not change their skin colour without any pain
B. the new discovery could lead to search into ways to change skin colour safely
C. pop king Michael Jackson often changed his skin colour as he liked
D. scientists have found out that people’s skin colour is determined by the gene
2.. Scientists have done an experiment on a dark-striped zebra fish in order to ________.
A. find the different genes of humans’
B. prove the humans’ skin colour is determined by the pigment gene
C. find out the reason why the Africans’ skin colour is dark
D. find out the ways of changing peopl’s skin colour
3.. The reason why Europeans are light-skinned is probably that ________.
A. they are born light-skinned people
B. light-skinned Europeans have mutation in the gene for melanosome production
C. they have fewer activities outside
D. they pay much attention to protecting their skin
For many people in the US，sports are not just for fun. They’re almost a “religion”．Thousands of sports fans buy expensive tickets to watch their favorite teams and athletes play in person .Other fans watch the games at home，sticking to their TV sets，never missing a game. Many a wife becomes a “sports widow” during her husband’s favorite season. Americans’ devotion to sports has created a new class：professional athletes. Sports stars often receive milliondollar salaries. Some even make big money by appearing in advertisements for soft drinks，shoes and almost everything.
Sports are an important part of American culture. Throughout their school life，Americans learn to play many sports. Many students try out for the school teams. Athletic events at universities attract scores of fans and benefit the whole community. Many people also enjoy noncompetitive activities，like hiking，cycling，horseback riding，camping or hunting.
Many sports were imported from other countries. Europeans brought tennis，golf，bowling and boxing to America .Football and baseball came from other Old World games. Only basketball has a truly American origin. Americans export sports fever as well. Satellites broadcast games to sports fans around the globe. NBA is a good example. The names of American superstars like basketball great Michael Jordan have become household words all over the world.
1.．Many a wife becomes a “sports widow” in the US probably because________.
A．they are serious in religion
B．they are devoted to sports
C．their husbands stick to sports
D．their husbands are missing
2.．Which of the following is NOT true according to the passage?
A．The US sports stars can earn a large sum of money via the media.
B．American students go in for various sports and athletic events.
C．Lots of American people take part in noncompetitive activities.
D．American people like to exchange different sports from each other.
3.．The writer mainly intends to tell us________.
A．how important sports are in America
B．where sports can help to make money
C．why sports are so popular in America
D．what affect Americans’ everyday life
Far from the land of Antarctica, a huge shelf of ice meets the ocean. At the underside of the shelf there lives a small fish, the Antarctic cod.
For forty years scientists have been curious about that fish. How does it live where most fish would freeze to death? There must be some secrets. The Antarctic is not a comfortable place to work and research has been slow. Now it seems we have an answer.
Research was begun by cutting holes in the ice and catching the fish. Scientists studied the fish's blood and measured its freezing point.
The fish were taken from seawater that had a temperature of -1.88℃ and many tiny pieces of ice floating in it. The blood of the fish did not begin to freeze until its temperature was lowered to -2.05℃. That small difference is enough for the fish to live at the freezing temperature of the ice-salt mixture.
The scientists' next research job was clear: find out what in the fish's blood kept it from freezing. Their search led to some really strange things made up of a protein(蛋白质) never seen in the blood of a fish before. When it was removed, the blood froze at seawater temperature. When it was put back, the blood again had its antifreeze quality and a lowered freezing point.
Study showed that it is an unusual kind of protein. It has many small sugar molecules(分子) held in special positions within each big protein molecule. Because of its sugar content, it is called a glycoprotein. So it has come to be called the antifreeze fish glycoprotein, or AFGP.
1. What is the text mainly about?
A. The terrible conditions in the Antarctic. B. A special fish living in freezing waters.
C. The ice shelf around Antarctica. D. Protection of the Antarctic cod.
2. Why can the Antarctic cod live at the freezing temperature?
A. The seawater has a temperature of -1.88℃.
B. It loves to live in the ice-salt mixture.
C. A special protein keeps it from freezing.
D. Its blood has a temperature lower than -2.05℃.
3. What does "glycol-" in the underlined word "glycoprotein" in the last paragraph mean？
A. sugar B. ice C. blood D. molecule
American cities are similar to other cities around the world. In every country cities reflect the values of the culture. Cities contain the very best aspects of a society: opportunities for education employment and entertainment. They also contain the very worst parts of a society: violent crime, racial(种族) conflict and poverty. American cities are changing just as American society is changing.
After World War II city residents became wealthier. They had more children. They needed more space. They move out of their apartments in the city to buy their own homes. They bought houses in the suburbs areas near a city where people live. These are areas without many offices or factories. During the 1950s the American “dream” was to have a house in the suburbs.
Now things are changing. The children of the people who left the cities in 1950s are now adults. They unlike their parents want to live in the cities. Many young professionals, doctors, lawyers and executives(主管人员) are moving back into the city. Many are single; others are married but often without children. They prefer the city to the suburbs because their jobs are there; they are afraid of the fuel shortage; or they just enjoy the excitement and opportunities which the city offers.
This population shift(转变) is bringing problems as well as benefits. Countless poor people must leave their apartments in the city because the owners want to sell the buildings or make apartments for sale instead of for rent. In the 1950s, many poor people did not have enough money to move to the suburbs; now many of these people do not have enough money to stay in the cities.
Only a few years ago, people thought that the older American cities were dying. Some city residents now see a bright, new future. Others see only problems and conflicts. One thing is for sure：many dying cities are alive again.
1. What does the author think of cities all over the world?
A. They are alive. B. They are hopeless.
C. They are similar D. They are different.
2.Why did American city residents want to live in the suburbs after World War II?
A. Because older American cities were dying.
B. Because they were richer and needed more space.
C. Because cities contained the worst parts of society.
D. Because they could hardly afford to live in the city.
3. According to the 4th paragraph, a great many poor people in American cities ___________.
A. are faced with housing problems
B. are faced to move to the suburbs
C. want to sell their buildings
D. need more money for daily expenses
4. We can conclude from the text that ____________.
A. American cities are changing for the worse
B. people have different views on American cities
C. many people are now moving from American cities
D. the population is decreasing in older American cities
