2014华南师大附中高三英语综合测试 1(9)

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Sharks have lived in the oceans for over 450 million years, long

before dinosaurs appeared. There are now about 360 species of sharks, whose size, behavior, and other characteristics differ widely.

Every year, we catch and kill over 20140 million sharks, mostly for food and for their fins. Dried shark fins are used to make shark fin soup, which sells for as much as $50 a bowl in fine Hong Kong restaurants. Other sharks are killed for sport and out of fear. Sharks are vulnerable to overfishing because it takes most species 2014 to 15 years to begin reproducing and they produce only a few offspring.

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 shark injure about 20140 people worldwide and kill about 25. Most attacks are by great white sharks, which often feed on sea lions and other marine mammals. 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 20140 million. You are more likely to be killed by a pig than a shark and thousands 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, 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. Understanding why can help us improve human health. Chemicals extracted from shark cartilage have killed

cancerous tumors in laboratory animals, research that someday could help prolong your life.

Sharks are needed in the world’s ocean ecosystems. 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.