Questions 15-18 are based on the following dialogue: Why do dolphins use clicks A: To communicate with other dolphins. B: To recognize objects in the water. C: To learn human language. D: To express fear.

What can we learn from the first paragraph（） A: A dolphin is a special kind of fish. B: Dolphins can"t swim very quickly. C: Dolphins can live only in the sea. D: Dolphins produce their babies on land.

Climate change was probably important in both ______ and evolution of dolphins. A: execution B: extinction C: exclusion D: excavation

In the zoo if a child （ ） into the water and can’t swim, the dolphins may come up （ ）him.

The astronomer was not interested in the way dolphins communicate with each other. A: Right B: Wrong C: Not mentioned

Climate change was probably important in both ______ and evolution of dolphins. A: execution B: B. extinction C: C. exclusion D: D. excavation

Which of the following activities will negatively influence animals？（ ） A: hunting B: wildlife observation C: swimming with dolphins D: scuba diving on reefs

In the zoo if a child _____ into the water and can’t swim, the dolphins may come up ______ him. A: will fall; to help B: falls; to help C: will fall; help D: falls; helping

Dolphins once were hunted for money because______. A: they are rare and precious animals B: valuable oil can be obtained form their head C: they can produce oil for lubrication D: they are able to utter sounds worth study

Which of the followings is NOT TRUE A: A dolphin can stay under the water for about six minutes. B: A dolphin often comes to the top of the water to take in air. C: Dolphins are not fish but mammals in the sea. D: A dolphin doesn't have a good hearing.