第17题: [单项选择]Questions 33 to 35 are based on the passage you have just heard. A. As the fleets of the sea. B. As being very intelligent. C. As the top of the land food chain. D. As the top of the ocean food chain. 参考答案:D 答案解析:[听力原文] 33-35 [33]Sharks have been at the top of the ocean food chain for millions of years