题目内容：

Over 2,200 years ago, Chengdu was threatened by frequent floods. Li Bing, together with his son, decided to construct an irrigation system on the Minjiang River1. (prevent) flooding.  2.having a long study and a lot of hard work by the local people, the great Dujiangyan Irrigation System was completed. Since then, the Chengdu Plain 3. (be) free of flooding and the people have been living peacefully and wealthily.

It is the4. (old) and only surviving no-dam irrigation system in the world. It is also 5. wonder in the development of Chinese science. The project consists of three important parts，namely Yuzui, Feishayan and Baopingkou, which were 6.(science) designed to control the water flow of the rivers throughout the year.

There is a glorious bridge called the Anlan Cable Bridge crossing the Minjiang River above Yuzui, 7. you can clearly see the entire system. The great 8. (construct) originally started before the Song Dynasty. At that time, the body of the bridge was constructed with wooden blocks and the handrails(扶手)were made of bamboo. Recently the wood and bamboo have been replaced with steel and concrete to guarantee the security of 9.(visit) from home and abroad. Seen from afar, the bridge looks like a rainbow 10.(hang) over the river.