In northern China during spring, big sandstorms often make trouble for people. Sandstorms usually happen in spring. They have happened in more than 10 provinces in northern China this year. People in southern China don't have to worry about this kind of bad weather. Most of the sand comes from the north of China. In northern China, lots of places have few trees and don't get much rain. When there aren't many trees, the ground can't keep enough water. Over the years, the ground dries up and turns into sand. When spring comes and the ice melts, the ground becomes loose. Strong winds take the loose sand into the sky. Besides, in northeast China, there is some vast desert. Sandstorms are bad for people's health. If people breathe in too much sand, they will cough or have serious illnesses. Sandstorms also give farmers lots of problems. Sometimes their sheep get lost in the storms and never come back home. The winds also tear the farmers'  houses down. What can you do to stop sandstorms? Here's a piece of advice. Ask your parents to help you plant some trees in spring. If you see people cutting down too many trees, tell them about the dangers of sandstorms, and ask your government to stop them. Which is the best title for this passage?  _
Sandstorms How we can stop sandstorms Why sandstorms only happen in northern China. Sandstorms can influence most of China.