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.
The passage mainly discusses ______.

选项 A、the number of people being attacked by sharks
B、the benefits of sharks to improving human health
C、the dangers sharks have brought to human beings
D、the relationship between sharks and human beings

答案D

解析 主旨题。选项A、B和C都过于片面,不能概括出文章的主题。答案为D。
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