Question

The people of Chicago, Illinois, US, can thank three canals every time they drink a glass of clean water today. The building of the Illinois-Michigan Canal, the Chicago Sanitary and Ship Canal and the Cal-Sag Canal all helped the Chicago River start flowing in a different direction in 1892.

Since their construction over a century ago, these waterways have connected Lake Michigan and the Mississippi river network and ensured a regular flow of fresh water of Chicago.

However, some unusual and unfortunate side effects have also been created because of their construction. Asian carp(鲤鱼), also known as silver or flying carp, are threatened in their native habitat in the Chinese Heilongjiang, Yangtze, and Pearl River basins. But they have become increasingly successful at filling the Mississippi river network since first being introduced into Arkansas catfish farms in the 1970s to control algae(水藻). By swimming into the canals and spreading further across the country, there are now major fears that this introduced species may be able to access Lake Michigan and the wider Great Lakes - which store an incredible 21 percent of the entire world’s fresh water.

“The actual influence of Asian carp on the Great Lakes has yet to be explained clearly, and we think this uncertainty is part of the reason why they are such an obvious issue,” says Dr Cory Suski, Associate Professor in the Department of Natural Resources and Environment Sciences at the University of Illinois. He points out that adult Asian carp are too large to be hunted by anything locally, that they have a prolific(多产的) reproduction rate, and they can steal food from the other native species in the rivers. “Could they survive in the Great Lakes or is there not enough food for them?” he asks.

Stopping the fish from spreading has therefore become a key concern for local lawmakers, who have made efforts such as building electric fences in the Chicago Sanitary and Ship Canal. However, any big efforts to stop the carp - such as allowing the Chicago River to once again flow in its original direction - would in turn threaten the security of the city’s water supply, replacing one big problem with another.

1.According to the text, the construction of the three canals      .

A. changed the direction of the Mississippi river.

B. brought fresh water to the people of Chicago.

C. lasted for almost a century because of huge cost.

D. has been the largest construction project in US history.

2.According to the text, Asian carps      .

A. have nearly become extinct in Chinese rivers.

B. have occupied large areas in the Great Lakes.

C. were introduced to the US to fight against algae pollution.

D. are likely to pollute the fresh water in the Great Lakes.

3.What is the major concern of Asian carp in the US?

A. Its large size and fast reproduction rate.

B. The food shortage facing the species.

C. Its threat to the Great Lakes ecosystem.

D. Its natural enemies in the local areas.

4.What can we infer from the last paragraph?

A. US law makers knew little of the threat caused by Asian carp.

B. Electric fences might not be enough to stop the spread of Asian carp.

C. The Chicago River has changed its flowing direction many times.

D. People in Chicago will soon face a serious water supply shortage.

Answer

1.B

2.C

3.C

4.B

【解析】

本文是一篇说明文。讲述了伊利诺斯-密歇根运河、芝加哥环境卫生和航行运河和奇运河的建设给芝加哥带来了淡水，但是一些不寻常的的副作用也因为它们的建设而产生：亚洲鲤鱼在芝加哥水域不断蔓延影响当地水域的生态平衡。

1.细节理解题。根据第一段The people of Chicago, Illinois, US, can thank three canals every time they drink a glass of clean water today.以及第二段﹍and ensured a regular flow of fresh water of Chicago.可知三个运河的建设给芝加哥人民带来了淡水。故选B。

2.细节理解题。根据第三段But they have become increasingly successful at filling the Mississippi river network since first being introduced into Arkansas catfish farms in the 1970s to control algae.可知亚洲鲤鱼一开始被美国引进是为了控制藻类污染。故选C。

3.细节理解题。根据第四段He points out that adult Asian carp are too large to be hunted by anything locally, that they have a prolific reproduction rate, and they can steal food from the other native species in the rivers.可知亚洲鲤鱼由于尺寸大以及繁殖率快，威胁了五大湖的生态系统，故选C。

4.推理判断题。根据最后一段However, any big efforts to stop the carp - such as allowing the Chicago River to once again flow in its original direction - would in turn threaten the security of the city’s water supply, replacing one big problem with another.可知包括设置电丝网在内的任何措施都没有有效的阻止亚洲鲤鱼的蔓延，故选B。