Question

13．Does the Yangtze River still have baiji（白鳍豚），the graceful，grey dolphin with tiny eyes and a long narrow beak？
Since November 6，a team of scientists from China，Switzerland，the United Kingdom，the United States，Germany and Japan had been searching for any sign of the freshwater dolphin in the middle and lower sections of the river．After six weeks，they came back empty-handed．Wang Ding，head of the team，said he had seen a sharp drop in the baiji population over the past few decades．However，he was still unwilling to call the species extinct and added，"We will try every effort to save them as long as they are not found to be extinct．"
As one of the world's oldest dolphin species，the baiji is shy and nearly blind．It dates back about 20 million years and is found only in the Yangtze River．It's listed as one of the 12 most endangered animal species in the world．
Around 400 baiji were believed to be living in the Yangtze until the 1 980s．In 1997，a survey spotted 13．Two years later their number was down to zero．
  The rapi d disappearance of this dolphin over the past two decades coincided（巧合） with the rapid expansion of economic development along the river．Resea rchers on some dead baiji collected in recent years showed that more than 90 percent of the deaths were caused by human activities．
One reason is that over-fishing has cut the dolphin's food sources．Dams built along the river and neighbouring waterways have also kept them from swimming into and out of their habitats．Meanwhile，waste discharge（排放） has seriously polluted the river．And heavy river traffic has greatly reduced their living space．
The disappearance of the baiji would be the first case of a large aquatic（水生的） mammal being driven to extinction since hunting killed off the monk seal around 1952．
42．This passage mainly tells usA．
A．the fact that Baiji is in danger and the reason why its number reduces
B．people are trying efforts to save Baij i as long as they find them
C．human activities have caused 90 percent of Baiji's deaths
D．how serious the pollution is long the Yangtze River
43．It is known from the passage thatB．
A．scientists from foreign countries have searched for Baiji for 6 years
B．Baiji is a large aquatic mammal which is in danger of extinction
C．Baiji becomes endangered all because of human's activities
D．there are 12 endangered species altogether in the world
44．We can infer from the passage thatA．
A．riverside constructions have affected the living environment of animals
B．Baiji is one of the world's oldest species and lives longer than humans
C．it is the waste discharge that has poisoned Baiji in Yangtze River
D．nowadays scientists are no longer able to save Baiji at all
45．This passage is most probably taken fromD．
A．a student's diary              B．a tour guidebook
C．a Biology textbook              D．a science magazine．

Answer 1

分析 本文主要讲述了目前长江的白鳍豚处境危险、数量减少及其原因．

解答 42-45．ABAD
42题答案：A 考查文章大意，纵观全文可知，文章主要讲的是白鳍豚处境危险的事实及其数量减少的原因，故本题答案为A选项．
43题答案：B 考细节推理，根据最后一段的The disappearance of the baiji would be the first case of a large aquatic（水生的） mammal being driven to extinction （白鳍豚的消失有可能是第一个大型水生哺乳动物被逼灭绝的案例）可知本题答案为B选项"白鳍豚是一种面临灭绝的大型水生哺乳动物"．
44题答案：A 考查细节推理，根据倒数第二段的Dams built along the river and neighbouring waterways have also kept them from swimming into and out of their habitats．（沿河的大坝建设以及邻近的水路也阻止了它们出入栖息地）可知本题答案为A选项"河边的建设影响了动物的居住环境"．
45答案：D 考查文章来源 本文是一篇有关海豚是否还存在于长江的科学类研究文章，故应该取自于"科学杂志"，因此本题答案为D选项．

点评 本文是一篇科普类阅读，题目涉及多道细节理解题，做题时结合原文和题目有针对性找出相关语句进行仔细分析，结合选项选出正确答案．推理判断也是要在抓住关键句子的基础上合理的分析才能得出正确的答案．