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    1    is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6000 square kilometers of farmland and provide water for 50 cities in the province.

In ancient times, the region in which Dujiangyan now stands suffered from regular floods     2    (cause) 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    3    (solve).

Li designed a series of channels built at different levels along Mount Yulei    4    would take away floodwater while    5    (leave) the river flowing naturally.    6    (Well) still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

After eight years of work, the 20-meter-wide canals had been carved through the mountain.

Once the system was finished, no more floods     7     (occur) and the people were able to live peacefully and    8    (happy).Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water    9    (block) with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish population to exist       10     harmony.