四级冲刺练习阅读（172）

　　There can be no doubt that sharks hear perfectly. Experience has shown that they react to the sound of blows under water, to the sound of a bell, or to the noises made by a diver at work. In general, their reaction is one of intense interest. I have often tried bits of advice like If you see a shark approaching, beat the water with your hands, or the famous warning given to beginning divers, If you want to drive a shark away, cry out in the water. In my experience, such advice is almost criminal. In most cases the consequence was an immediate attack.

　　There seems to be no reason for the sharks frenzy. This, I think, is what hits me most, giving me a feeling of complete helplessness. The mad rush of hordes of sharks toward the exact point where one of their own has devoured a bit of fish is terrifying to watch. The beasts seem unstoppable and fatal and totally senseless.

　　Sometimes the shark will flee from a naked and unarmed diver, and at other times he will throw himself against a steel diving cage and hit furiously at the bars. With any other animal be it dog or crow I know that my actions or

　　reactions will have a direct influence on its behavior. But the shark moves through my world like a puppet whose strings are controlled by something other than the power moving mine; he seems to come from another planet. In fact, he does come from another time in that he has evolved little since his beginning. He perfectly adapts to his life, yet no one can ever predict what he will do.

　　We do not know if sharks migrate from one region to another, but it has been established that the majority swim unceasingly, day and night. There are two reasons for this. Sharks do not have a swimming bladder . If sharks stop swimming they will sink. Also, most species have no mechanism for pumping water so that it will pass over their gills and bring oxygen into the bloodstream. They must depend on constant movement for this breathing.

　　26. According to the writer, if we see a shark approaching, we should_______.

　　A. cry out in water B. ring a bell

　　C. beat the water with our hands D. keep silent

　　27. Which of the following adjectives can best describe the sharks rush towards the spot where some blood is?

　　A. Criminal. B. Senseless.

　　C. Helpless. D. Terrified.

　　28. In Paragraph 3, the writer describes the behavior of sharks in order to show_______.

　　A. the influence of its behavior B. the adaptation of its behavior

　　C. the unpredictability of its behavior D. its difference from dog or crow

　　29. Which of the following statements about sharks is TRUE?

　　A. They are various kinds of puppets.

　　B. Most of them swim from one place to another every year.

　　C. Most of them keep on swimming without stopping.

　　D. Most of them have a swimming bladder.

　　30. The word frenzy most probably means_______.

　　A. helplessness B. madness

　　C. terror D. rush

　　26. D 27. B 28. C 29. C 30. B