Dujiangyanistheoldestman-madewatersystemintheworld,anda...

问题详情：

Dujiangyan is the oldest man-made water system in the world, and a wonder in the development of Chinese science. Built over 2,200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6,000 square kilometres of farmland, take away floodwater and provide water for 50 cities in the province.

In ancient times, the region in which Dujiangyan now stands suffered from regular floods caused by overflow from the Minjiang River. To help the victims of the flooding, Li Bing, the region governor, together with his son, decided to find a solution. They studied the problem and discovered that the river most often overflowed when winter snow at the top of the nearby Mount Yulei began to melt as the weather warmed.

The simplest fix was to build a dam, but this would have ruined the Minjiang River. So instead Li designed a series of channels built at different levels along Mount Yulei that would take away the floodwater while leaving the river flowing naturally. Better still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

Cutting the channels through the hard rock of Mount Yulei was a remarkable accomplishment as it was done long before the invention gunpowder and explosives. Li Bing found another solution. He used a combination of fire and water to heat and cool the rocks until they cracked and could be removed. After eight years of work, the 20-metre-wide canals had been carved through the mountain.

Once the system was finished, no more floods occurred and the people were able to live peacefully and affluently. Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish populations to exist in harmony.

4. What are the benefits of Dujiangyan according to the first paragraph?

A. Reducing flooding and watering farmland.

B. Protecting the mountain and reducing flooding.

C. Watering farmland and improving water quality.

D. Drying the river and supplying cities with water.

5. What was the main cause of the Minjiang Rivers flooding?

A. Heavy rains.       B. Melting snow.

C. Low river banks.    D. Steep mountains.

6. How was Li Bing able to break through the rocks of Mount Yulei?

A. By using gunpowder.

B. By flooding the rocks with water.

C. By applying a heating and cooling technique.

D. By breaking the rocks with hammers and spades.

7. Why is Dujiangyan greatly admired by scientists today?

A. It preserves much of the natural river life.

B. It took very little time to complete the project.

C. The building techniques used were very modem.

D. It has raised the living standards of the local people.

【回答】

ABCA

知识点：阅读理解

题型：阅读理解