2．Some scientists say that animals in the ocean are increasingly threatened by noise pollution caused by human beings．The noise that affects sea creatures comes from a number of human activities．It is caused mainly by industrial underwater explosions，ocean drilling，and ship engines．Such noises are added to natural sounds．These sounds include the breaking of ice fields，underwater earthquakes，and sounds made by animals themselves．
Decibels （分贝） measured in water are different from those measured on land．A noise of one hundred and twenty decibels on land causes pain to human ears．In water，a decibel level of one hundred and ninety-five would have the same effect．
Some scientists have proposed setting a noise limit of one hundred and twenty decibels in oceans．They have observed that noises at that level can frighten and confuse whales．
A team of American and Canadian scientists discovered that loud noises can seriously injure some animals．The research team found that powerful underwater explosions were causing whales in the area to lose their hearing．This seriously affected the whales'ability to exchange information and find their way．Some of the whales even died．The explosions had caused their ears to bleed and become infected．
Many researchers whose work depends on ocean sounds object to a limit of one hundred and twenty decibels．They say such a limit would mean an end to important industrial and scientific research．
Scientists do not know how much and what kinds of noises are harmful to ocean animals．However，many scientists suspect that noise is a greater danger than they believed．They want to prevent noises from harming creatures in the ocean．
29．According to the passage，which of the following is increasingly dangerous to sea creatures？A
A．The man-made noises．
B．The noises made by themselves．
C．The sound of earthquakes．
D．The sound of the ice-breaking．
30．As to the influence of noises on whales，which of the following statements is true？B
A．They are deaf to noises．
B．Noises may hurt them．
C．Noises will limit their ability to reproduce．
D．They are confused by a noise of 120decibels in oceans．
31．We can know from the passage that many scientists think that the noise limit of one hundred twenty decibels wouldA．
A．prevent them from doing their research work
B．benefit （有益于） them a lot in their research work
C．do good to their health
D．increase the industrial output
32．According to the passage，what will scientists most probably do in the future？B
A．They will try their best to make noise．
B．They will work hard to cut down noise pollution．
C．They will study the effect of different noises．
D．They will study the underwater earthquakes．
分析 本文是一篇科普类文章，主要讲述了噪声污染会对海洋生物造成伤害，科学家不知道什么强度什么种类的噪音会对海洋生物造成伤害，然而，许多科学家怀疑噪音比想象中的危害更严重，未来他们希望能减少噪音以防止伤害海洋生物．
解答 29．答案：A．细节理解题．根据"Some scientists say that animals in the ocean are increasingly threatened by noise pollution caused by human beings"知，噪声污染对海洋生物有害．故选A．
30．答案：B．细节理解题．根据"They have observed that noises at that level can frighten and confuse whales"知，一定程度的噪音可能会伤害鲸鱼．故选B．
31．答案：A．细节理解题．根据"Many researchers whose work depends on ocean sounds object to a limit of one hundred and twenty decibels．They say such a limit would mean an end to important industrial and scientific research"可知，一百二十分贝的噪音限制阻止他们做他们的研究工作．故选A．
32．答案：B．推理判断题．根据"However，many scientists suspect that noise is a greater danger than they believed．They want to prevent noises from harming creatures in the ocean．"可推测出，科学家未来可能会努力减少噪声污染．
点评 本文是一篇科教类阅读，题目涉及多道细节理解题，推理判断题，做题时应结合文章上下文内容，仔细阅读原文，并根据所给选项的含义进行分析，从而得出正确答案．切记胡乱猜测，一定要做到有理有据．
