（一）SharksPerformaServiceforEarth'sWaters.根据材料，回答下列问题。Itishardtogetpeopl

共享题干题 （一）Sharks Perform a Service for Earth's Waters.根据材料，回答下列问题。 It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to________ (51 )people frequently. But these fish perform a ________ (52 )service for earth's waters and for human beings. Yet business and sport fishing are threatening their________ (53). Some sharks are at________ (54) of disappearing from earth. Warm weather may influence both fish and shark activity. Many fish swim near coastal areas________ (55 ) their warm waters. Experts say sharks may follow the fish into the same areas,________ (56)people also swim. In fact,most sharks do not purposely charge at or bite humans. They are thought to mistake a person________ ( 57 ) 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________ (58 )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________ (59)produced by animals. These powerful________ (60) help sharks find their food. Sharks eat fish, any________ ( 61 ) sharks ,and plants that live in the ocean. Medical researchers want to learn more about the shark's body defense and immune systems________ .(62) disease. Researchers know that sharks ________ (63)quickly from injuries. They study the shark in hopes of finding a way to fight human disease.Sharks are important for the world's________ .(64). They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too________ (65). This protects the plants and other forms of life that exist in the oceans.1.[不定向选择题]________________A.recover B.reform C.return D.rely 2.[不定向选择题]________________A.rivers B.oceans C.forests D.mountions

1.参考答案：A
参考解析：本段最后一句的意思是：医学研究人员研究鲨鱼的目的是为了找到一种人类抗病的方法。所以，空格所在句子的意思应该是recover(quickly from injuries)。科学家想要探索的应该是有关受伤鲨鱼recover quickly from injuries的秘密，而reform(改造)、return(回归)和rely(依靠)只是与答案recover在词形上有点相似而已，其意思与上下文的意思风马牛不相及。
2.参考答案：B
参考解析：从上下文判断，鲨鱼的存在能使0ceans得益。鲨鱼不生活在river，forests或mountains中，所以这三个选项不会是答案。3.[不定向选择题]________________A.sciences B.mathematics C.chemicals D.physics

就是这个解释