Influenced by movies and popular novels, most people see sharks as people-eating monsters. This is far from the truth. Every yea

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问题     Influenced by movies and popular novels, most people see sharks as people-eating monsters. This is far from the truth. Every year, a few types of sharks injure about 100 people worldwide and kill about 25. Most attacks are by great white sharks, which often feed on sea lions and other marine mammals (海洋哺乳动物) . They sometimes mistake human swimmers for their normal prey, especially if they are wearing black wet suits.
    If you are a typical ocean-goer, your chances of being killed by an unprovoked attack by a shark are about 1 in 100 million. You are more likely to be killed by a pig than a shark and thou sands of times more likely to get killed when you drive a car.      Sharks help save human lives. In addition to providing people with food, they are helping us learn how to fight cancer, bacteria (细菌), and viruses. Sharks are very healthy and have aging processes similar to ours. Their highly effective immune system allows wounds to heal quickly without becoming infected, and their blood is being studied in connection with AIDS research.
    Sharks are among the few animals in the world that almost never get cancer and eye cataracts (白内障).  Understanding why can help us improve human health.  Chemicals extracted from shark cartilage (软骨) have killed cancerous tumors in laboratory animals, research that someday could help prolong your life.
    Sharks are needed in the world’ s ocean ecosystem. Although they don’ t need us, we need them. We are much more dangerous to sharks than they are to us. For every shark that bites a person, we kill one million sharks.
According to the passage, we need sharks because of the following except ______.

选项 A、they are delicious food for us
B、they are companions of human beings
C、they can help rescue human beings
D、they can help improve human health

答案B

解析 细节题。根据第三段第一句Sharks help save human lives,第二句In addition to pro viding people with food,和第四段第二句Understanding why can help us improve human health可知选项A、C、D俱为我们需要鲨鱼的原因,故答案为B。
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