[单项选择]A scorching sun, an endless sea of sand and a waterless, forbiddingly lonely land—that is the image most people have of deserts. But how true is this picture Deserts are dry lands where rainfall is low. This is not to say rain never falls in deserts: it may fall once or twice a year in a fierce torrent that fades almost as soon as it has begun, or which evaporates in the hot air long before it has got anywhere near the earth. It may fall in a sudden sweeping flood that carries everything in its path. Rains may only come once in five or six years or not fall for a decade or more. The Mojave desert in the United States remained dry for twenty-five years.
Without water no living thing can survive, and one feature of the true desert land-scape is the absence of vegetation. With little rain and hardly any vegetation the land suffers under the sun. There are virtually no clouds or trees to protect the earth’s surface and it can be burning hot. Under the sun, soils break up and crack. Wi
A. It is a natural development.
B. The problem is not very serious.
C. It is a very worrying problem.
D. The situation will improve in tim