C．People can't breathe well and the dust makes them ill.

D．All of the above.

答案　D

4．What is the best way to avoid the effects from the sandstorm?

A．To live far away from deserts.

B．To stay at home when a sandstorm happens.

C．To wear a mask if you want to go out.

D．To plant more trees.

答案　D

5．Which of the following is NOT the element to make Central Asia，North America，Central Africa and Australia the four main places where there are sandstorms?

A．The climate in these places is rather bad.

B．They are all the places with big deserts.

C．The natural environment in these places is worsening every year.

D．The governments in these places pay little attention to the protection of nature.

答案　D

Ⅳ.课文难句分析

This is a process that happens when land becomes desert because of climate changes and because people cut down trees and dig up grass.

[句式分析]　本句是一个复合句。主句是This is a process；that happens...为定语从句修饰process；when land...为时间状语从句；because of climate changes和because people cut down trees and dig up grass分别是原因状语和原因状语从句。

[自主翻译]　这是一个因气候变化和人类砍树挖草导致土壤沙化的过程。

　　In recent years，with the development of economy and the society，the environment is getting worse and worse.There are more and more sandstorms in our country，especially in the north.It's high time we should take measures to reduce sandstorms and protect our home.What measures should we take to prevent sandstorms? Do a survey in your school or in your community and then write a report on how we should do to achieve our goal.The following tips may help you：

1．We should plant more trees and grow more grass.

2．Control air and water pollution.

3．Build green fences along the desert.

4．Forecast sandstorms' real time to prevent disasters.

5．Establish sandstorms data bank and collect information about sandstorms.

6．All countries should join hands to propose a plan in sandstorms' control and prevention.