3. He heats the water over fire to make it safe for drinking. (对画线部分提问)
________ ________ he heat the water over fire?

4. Little John often played chess with his grandpa in the past. (保持句义不变)
Little John ________ ________ play chess with his grandpa.

5. it is, I, to the nearby rock, when, full, take the pot (连词成句) ________

V. Read the passage and complete the tasks.
Built over 2,200 years ago in the Qin Dynasty, the Dujiangyan Irrigation System (都江堰水利工程) is one of the oldest and most famous water - projects in the world. In ancient times, the Min River often flooded. In order to make better use of the river water and solve the problem of floods and droughts (干旱), the Dujiangyan Irrigation System was built in 256 BC, which was designed by ancient Chinese engineer Li Bing.
The system divides the Min River into two parts: the inner part and the outer - part, which play different roles in dry and rainy seasons. During dry seasons, 60% of the river water runs into the inner part to water farms. In rainy seasons, the outer part carries 60% of the water, protecting the Chengdu Plain against floods. By changing the river way, the system cleverly controls the water. However, as water keeps running through, it leaves behind — lots of silt (淤泥). So, it's necessary to dig and clean the riverbed every year. When Dujiangyan was first built, Li Bing put Shima (stone horse) in the riverbed. It served as a ruler and told people how deep to dig when cleaning the riverbed.
In Ming Dynasty, the first Wotie (lying iron stick) appeared and took the place of Shima. In dry seasons, people cleaned away part of the earth and sand from the riverbed. When they dug down and reached the Wotie, they knew they could stop.
The tradition of digging the riverbed has been lasting for over 2,000 years. People continued to repair Dujiangyan, and new Woties were placed in the riverbed. Today, four Woties lie side by side underwater, which were made in different ages from Ming Dynasty to the new China. Although workers have better tools now, ________.
Task 1: Answer the questions.
1. Why was the Dujiangyan Irrigation System built?
________
2. Which part of the system plays an important role in rainy seasons?
________
3. How does the system take control of the water in the Min River?
________
4. What is the function of Shima?
________
5. How long has the tradition of digging the riverbed been lasting?
________
Task 2:
6. Complete the missing part in the last paragraph with about 30 words.
________