Special trees that grow faster, fight pollution, produce better wood, and even sense chemical attacks are being planted by scientists in the US．

????????????? When 40 per cent of Hawaii's US$14 million-a-year papaya （木瓜）industry was destroyed by a virus five years ago, work began on creating genetically engineered（转基因的）trees．

????????????? Researchers successfully introduced seeds that were designed to resist the virus．Since then, more and more people have been testing genetically engineered trees．Some researchers put special bacteria into trees to help them grow faster and produce better wood．Others are trying to create trees that can clean polluted soil．Meanwhile fruit farmers are looking for trees that are strong enough to resist worms, and paper companies want trees that produce more wood and therefore more paper．

????????????? The Pentagon （五角大楼） even gave the researchers US$500,000 this year after they developed a pine tree that changes its colours if it senses a chemical attack．So far, the poplar, eucalyptus （杨树与桉树）, apple and coffee trees are among those being engineered．All this can be done today because we have a better understanding of tree genomes （基因组）．

????????????? However, some people fear that the genetically engineered trees will cause dangerous results．They are worried that the new trees will breed with natural species and change the balance of the forest environment．

????????????? “It could be destructive,” said Jim Diamond, an environmentalist. “Trees are what is left of our natural environment and home to many endangered species.”

????????????? But researchers insist that science could give nature a fighting chance against both natural and man-made dangers．They hope to answer the critics by stopping the new trees from breeding, so their effect on the environment can be controlled．

1.Which kind of tree is not the ones that scientists are planting in the US?

A．Trees that worms can't hurt．

B．Genetically engineered trees．

C．Trees that can resist wind better．

D．Trees that can protect themselves at a chemical attack．

2.What caused the American scientists to work on special trees?

A．Tree genomes are mapped out so scientists know how to improve trees．

B．Great numbers of trees have been lost due to attacks by viruses．

C．Researchers successfully introduced seeds designed to resist the virus．

D．They think science could give nature a fighting chance against both natural and man-made dangers．

3.Which of the following was probably the first kind of trees being engineered?

A．Papaya．????????????? ????????????? ????????????? B．Pine．????????????? ????????????? ????????????? C．Apple．????????????? ????????????? ????????????? D．Poplar．

4.Why did critics think engineered trees dangerous? Because ________．

A．these trees can destroy the balance of nature

B．everything except trees has been genetically engineered

C．trees are home to many endangered species

D．these trees may affect normal trees

Special trees that grow faster, fight pollution, produce better wood, and even sense chemical attacks are being planted by scientists in the US．

    When 40 per cent of Hawaii's US$14 million-a-year papaya （木瓜）industry was destroyed by a virus five years ago, work began on creating genetically engineered（转基因的）trees．

    Researchers successfully introduced seeds that were designed to resist the virus．Since then, more and more people have been testing genetically engineered trees．Some researchers put special bacteria into trees to help them grow faster and produce better wood．Others are trying to create trees that can clean polluted soil．Meanwhile fruit farmers are looking for trees that are strong enough to resist worms, and paper companies want trees that produce more wood and therefore more paper．

    The Pentagon （五角大楼） even gave the researchers US$500,000 this year after they developed a pine tree that changes its colours if it senses a chemical attack．So far, the poplar, eucalyptus （杨树与桉树）, apple and coffee trees are among those being engineered．All this can be done today because we have a better understanding of tree genomes （基因组）．

    However, some people fear that the genetically engineered trees will cause dangerous results．They are worried that the new trees will breed with natural species and change the balance of the forest environment．

    “It could be destructive,” said Jim Diamond, an environmentalist. “Trees are what is left of our natural environment and home to many endangered species.”

    But researchers insist that science could give nature a fighting chance against both natural and man-made dangers．They hope to answer the critics by stopping the new trees from breeding, so their effect on the environment can be controlled．

1.Which kind of tree is not the ones that scientists are planting in the US?

    A．Trees that worms can't hurt．

    B．Genetically engineered trees．

    C．Trees that can resist wind better．

    D．Trees that can protect themselves at a chemical attack．

2.What caused the American scientists to work on special trees?

    A．Tree genomes are mapped out so scientists know how to improve trees．

    B．Great numbers of trees have been lost due to attacks by viruses．

    C．Researchers successfully introduced seeds designed to resist the virus．

    D．They think science could give nature a fighting chance against both natural and man-made dangers．

3.Which of the following was probably the first kind of trees being engineered?

    A．Papaya．         B．Pine．           C．Apple．          D．Poplar．

4.Why did critics think engineered trees dangerous? Because ________．

    A．these trees can destroy the balance of nature

    B．everything except trees has been genetically engineered

    C．trees are home to many endangered species

    D．these trees may affect normal trees

完形填空

　　It is well known that smoking causes harmful side effects; however, we see thousands of smoking. Not only the elderly;  1 young people and children are under smoke, in order to show they  2 ——maybe smoking is a  3 of being a grown up.  4 smoking has become a serious social problem.

　　Our government has  5 called on people to  6 smoking. As a result, many have given up smoking.  7 , a lot more people are joining the ranks of smokers.  8 it is far from enough to  9 the matter to slogans(口号).  10 is necessary is a campaign  11 smoking.

　　First, I suggest, regulations  12 be made to forbid smoking in public places. In many cities smoking is not  13 in cinemas or in theatres. Smokers have to abide by(遵守)it,  14 they'll be fined. Why can't we  15 this as a good example to develop it in other public places  16 on the trains, in the offices, hotels and so on?

　　Secondly, stricter measures  17 taken to impose a tax  18 smokers for causing pollution.  19 we'll continue the fight against smoking in the  20 that one day smokers will fully realize the health dangers they face.

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Directions: For each blank in the following passage there are four words or phrases marked A,B,C and D. Fill in each blank with a word or phrase that best fits the context.

Being alone in outer space can be   36 . That is one reason why astronauts on solo(单独的) space flights were given plenty of work to keep them   37 . They were also in constant communication with people on the earth.   38 , being with people from whom you cannot get away might be even harder than being alone. This is what happens on long submarine(潜水艇) voyages. It will also happen on  39 space flights in the future. Will there be special problems of adjustment under such conditions?

Scientists have studied the reactions of men to one another during long submarine voyages. They have also found that the longer the voyage lasts, the more serious the problem of  40 is. When men are  41 together for a long period, they begin to feel   42  . Everyone has little habits of speaking and behaving that are ordinarily acceptable. In the limited space over a long period of time, however, these little habits may become very   43  .

Apparently, although no one wants to be  44 all the time, everyone needs some degree of privacy. When people are enclosed together, they are in what is called stress situation. That means that they are under an unusual amount of  45 or stress.

People who are well-adjusted are able to   46 stress situations better than others. That is one reason why so much care is taken in   47 our astronauts. These men undergo a long period of testing and training. One of the things tested is their behavior under stress, and thus they can do better than ordinary people.