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D
People have been wondering why elephants do not develop cancer even though they have lifespans（寿命）that are similar to humans, living for around 50 to 70 years.
    Now scientists believe they know why. A team at the University of Chicago, US has found that elephants carry a large number of genes that stop tumors（肿瘤）developing. To be precise, they found 20 copies of an anti-tumor gene called TP53 in elephants.  Most other species, including humans, only carry one copy.
    According to the research, the extra copies of the gene improved the animal’s sensitivity to DNA damage, which lets the cells quickly kill themselves when damaged before they can go on to form deadly tumors.
    “An increased risk of developing cancer has stood in the way of the evolution of large body sizes in many animals,” the study author Dr. Vincent Lynch told The Guardian. If every living cell has the same chance of becoming cancerous (癌变的), large creatures with a long lifespan like whales and elephants should have a greater risk of developing cancer than humans and mice. But across species, the risk of cancer does not show a connection with body mass.
    This phenomenon was found by Oxford University scientist Richard Peto in the 1970s and later named “Peto’s paradox（悖论）”. Biologists believe it results from larger animals using protection that many smaller animals do not.  In the elephant’s case, the making of TP53 is nature’s way of keeping this species alive.
    The study also found that when the same genes were brought to life in mice, they had the same cancer resistance as elephants. This means researchers could use the discovery to develop new treatments that can help stop cancers spreading or even developing in the first place.
    “Nature has already figured out how to prevent cancer,” said Joshua Schiffman, a biologist at the School of Medicine, University of Utah, US. “It’s up to us to learn how different animals deal with the problem so that we can use those strategies to prevent cancer in people.”
32. Why are elephants unlikely to develop cancer?
    A. They have a rather large body size.
    B. Their genes suffer no DNA damage.
    C. Certain genes in their body kill existing tumors.
    D. They carry many genes to prevent tumors developing.
33. According to the passage, what has been a risk in the evolution of large animals?
    A. Deadly tumors.                    B. The huge body mass.
    C. Cells killing themselves.             D. Sensitivity to DNA damage.
34. What does the underlined part “This phenomenon” in Paragraph 5 probably refer to?
A. Larger animals have protection from TP53.
    B. The risk of cancer is not related to body size.
    C. Larger animals suffer the same risk of cancer as smaller ones.
    D. The larger animals are, the bigger risk of cancer they will have.
35. What can be concluded from the passage?
    A. Depending on nature is surely enough to fight against cancer.
    B. The TP53 genes have proved useful in stopping cancer in people.
    C. Humans are expected to prevent cancer with the making of TP53.
    D. The extra copies of elephants’ genes are used to cure cancer patients.
第二节 (共5小题;每小题2分，满分10分)
根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
    Possessing a car gives one a greater degree of freedom. With the building of good fast motorways, long distances can be covered rapidly and pleasantly.    36   You will no longer be forced to rely on public transport and work locally. You can choose from a greater variety of jobs and probably changes your work more frequently as you are not limited to a small area.
    Although you can afford to buy it now, you have to consider the future.    37   However large the first sum you have to pay, you have to spend more in running the machine—the various taxes, the fuel, and of course the repairs. The last is especially endless. Any single repair may cost you thousands.
      38   As more and more cars are produced and used, an even larger amount of poisonous gas is being sent out. Some of the contents of this gas, such as lead, can cause actual harm to the health of people. Many of the minor illness of modern industrial society, headaches, tiredness, and stomachaches may just arise from the gas. 高考英语模拟试题库  http://www.17xuexiba.com/yy/