Question

    Deserts are found where there is little rainfall or where rain for a whole year falls in only a few weeks' time. Ten inches of rain may be enough for many plants to survive if the rain is spread throughout the year, If it falls, within one or two months and the rest of the year is dry, those plants may die and a desert may form.

Sand begins as tiny pieces of rock that get smaller and smaller as wind and weather wear them down. Sand dunes are formed as winds move the sand across the desert. Bit by bit, the dunes grow over the years, always moving with the winds and changing the shape. Most of them are only a few feet tall, but they can grow to be several hundred feet high.

There is, however, much more to a desert than sand. In the deserts of the southwestern United States, cliffs and deep valleys were formed from thick mud that once lay beneath a sea more than millions of years ago. Over the centuries, the water dried up. Wind, sand, rain, heat and cold all wore away at the remaining rocks. The faces of the desert mountains are always changing—very, very slowly—as these forces of nature continue to work on the rock.

Most deserts have a surprising variety of life. There are plants, animals and insects that: have adapted to life in the desert. During the heat of the day, a visitor may see very few signs of living things, but as the air begins to cool in the evening, the desert comes to life. As the sun begins to rise again in the sky, the desert once again becomes quiet and lonely.

1.Many plants may survive in deserts when___________.

A.the rain is spread out in a year B.the rain falls only in a few weeks

C.there is little rain in a year D.it is dry all the year round

2.Sand dunes are formed when___________.

A.sand piles up gradually B.there is plenty of rain in a year

C.the sea has dried up over the years D.pieces of rock get smaller

3.The underlined sentence in the third paragraph probably means that in a desert there is____________.

A.too much sand B.more sand than before

C.nothing except sand D.something else besides sand

Answer

1.A

2.A

3.D

【解析】

本文是一篇说明文，介绍了关于沙漠的一些知识。

1.细节理解题。根据第一段中的“Ten inches of rain may be enough for many plants to survive if the rain is spread throughout the year”可知，如果全年都有降雨，那么10英寸的降雨量就足够让许多植物存活了，由此可知，当降雨量充足的时候，沙漠中的植物就能存活，故A项正确。

2.细节理解题。根据第二段中的“Sand dunes are formed as winds move the sand across the desert. Bit by bit, the dunes grow over the years,”可知，沙丘是风把沙子吹过沙漠而形成的，随着时间的推移，沙丘一点一点地变大，由此可知，沙丘是沙子逐渐堆积而成的，故A项正确。

3.词句猜测题。根据划线句后的“In the deserts of the southwestern United States, cliffs and deep valleys were formed from thick mud that once lay beneath a sea more than millions of years ago. Over the centuries, the water dried up. Wind, sand, rain, heat and cold all wore away at the remaining rocks.”可知，美国西南部的沙漠里，悬崖和深谷是由几百万年前埋在海底的厚厚的泥土形成的。几个世纪后，海水干涸了，风沙、雨水、冷热都侵蚀了剩下的岩石，这说明沙漠不仅仅是沙子，由此可知，划线句的意思是“除了沙子，沙漠里还有别的东西”，故D项正确。