阅读理解 Deserts are found where there is little rainfall or where rain for a whole

阅读理解

Deserts are found where there is littlerainfall or where rain for a whole year falls in only a few weeks’ time. Teninches of rain may be enough for many plants to survive(存活) if the rain is spread throughout theyear. 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 thatget smaller and smaller as wind and weather wear them down. Sand dunes(沙丘) are formed as winds move the sandacross the desert. Bit by bit, the dunes grow over the years, always movingwith 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 theSouthwestern United States, cliffs (悬崖)and deep valleys were formed from thick mud that once lay beneath a sea morethan 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 thedesert mountains are always changing—very, very slowly…as these forces ofnature continue to work on the rock.

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

1.Many plants may survive in desertswhen_____________.

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

A. itis dry all the year round

2.Sand dunes are formedwhen_____________.

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 thirdparagraph probably means that in a desert there is_____________.

A. too much sand  B.moresand than before

C.nothing except sand    D.somethingelse besides sand

4.It can be learned from the text that ina desert_____________.

A. there is no rainfall throughout theyear

B.life exists in rough conditions

C.all sand dunes are a few feet high

D.rocks are worn away only by wind andheat

试题答案

答案：A;A;D;B