3. How many ways do some experts put forward to fight against sandstorm?

　　A．5 B．4

　　C．3 D．2

　　解析：选C　细节理解题。根据文章第二段"For one thing, more funds (基金) ought to ..."和"For another, governments of all countries should make laws on environmental protection."以及"Scientists should also study and find ways to cut down the degree of its destruction and to improve the whole environment."说明文章中提出了3种方法，故C正确。

　　4．What's the author's attitude towards the situation to sandstorms' problems?

　　A．Unconfident. B．Optimistic.

　　C．Regretful. D．Satisfied.

　　解析：选B　推理推断题。根据文章最后"I am fully confident that the ... environment from today on."说明作者很有信心。故B正确。

　　B

　　Most of the sandstorms that had swept China last year came from foreign land, a Chinese official in charge of desertification (荒漠化) control said on Monday. And the invasions (入侵) could partly explain the frequent sandstorms in the country in recent years despite its achievements in desertification control.

　　Since the start of last spring, the north and northwestern Chinese regions had been hit by 17 sandstorms，of which, a dozen came from foreign land.

　　Situated in the central­Asia sandstorm region, one of the world's four largest sandstorm sources, China also suffers from sandstorms from outside the country while being blamed as a sand source to northeast Asia. The other three major sources are in Africa, North America and Australia.

　　The land suffering from desertification has been decreasing by 7,585 square kilometres annually in China, and the area of sandy land has also been falling by 1,284 square kilometres a year.

　　The shrinkage (收缩) forms a clear contrast to the fact that the land suffering from desertification and sandy feature was added by 10,400 square kilometres and 3,436 square kilometres late last century, respectively.

　　Currently, the desertification land in China makes up 2.64 million square kilometres, accounting for 27.46 percent of the nation's land, and its sandy land totals 1.74 million square kilometres, accounting for 18.1 percent of the country's total.

　　语篇解读：近年来中国遭受严重的风沙袭击，而中国也被认为是风沙的来源之一，经过努力中国在治沙方面取得显著的效果。

5．What does the underlined word "decreasing" mean in Paragraph 4?