题目内容：
阅读下文，回答题。Sharks Perform a Service for Earth‘s Waters
It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to 1 people frequently. But these fish perform a 2 service for earth‘s waters and for human beings. Yet business and sport fishing are threatening their 3 . Some sharks are at risk of disappearing from 4 ． Warm weather may influence both fish and shark activity. Many fish swim near coastal areas 5 their warm waters. Experts say sharks may follow the fish into the same areas, 6 people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person 7 a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the 8 _when sharks are looking for fooD． Experts also say that bright colors and shiny jewelry may cause sharks to attack. A shark has an extremely good sense of smell. It can find small amounts of substances in water, such as blood, body liquids and 9 produced by animals. These powerful 10_________ help sharks find their fooD． Sharks eat fish, any _11 sharks, and plants that live in the ocean.
Medical researchers want to learn more about the shark‘s body defense and immune 12 _against disease. Researchers know that sharks 13_________quickly from injuries. They study the shark in hopes of finding a way to fight human disease. Sharks are important for the world‘s 14 , They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too 15 __. This protects the plants and other forms of life that exist in the oceans.
请在（1）处填写正确答案。 A．attack
B．meet
C．love
D．visit
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