【阅读理解。阅读下列短文，并做每篇短文后的题目。从每小题所给的四个选项中选出能回所提问题或完成所给句子的最佳答案。Sincetheearliesttimestreeshavealwaysbeenveryusef】

　　阅读理解。

　　阅读下列短文，并做每篇短文后的题目。从每小题所给的四个选项中选出能回所提问题或完成所给句子的最佳答案。

　　Since the earliest times trees have always been very useful and important toman whomade use of them in many ways. Eventoday trees continue toserve man in so many ways. Trees provide manwith fruits andbuilding materials in the form of wood. Without trees it would be impossible to build houses boats and even bridges.Furniture such as tables chairs and beds aremade of wood.In the tropics(热带地区)whereitisveryhot all through the year trees protectman from the terrible heat. They are also useful in preventing the rich topsoilfrom being washed away during heavyrains which are so common in the tropics.If therewere notreesorvegetation(植被)ofsomekindstohold backthesoilwith theirrootsheavyrains would wash away the rich surface soil that is soimportant and necessary to agriculture(农业). The result isthatthelandbecomesa desert.Therearesomanydesert areas in theworld. Alongtime ago thesedesertareas must have been very rich fertile(丰产的)areas but since our ancestors(祖先)in the distant past didnot have a enoughknowledgeabout science of naturetheycut downallthetrees intheareaswheretheylived andneverplantednewones.Byandbytherichsurfacesoilwas blown away and washed away by strongwinds and heavy rains.Intheendtheland was turned into uselessdeserts where nothing could grow.

　　( )1、Iftherewerenotrees .

　　A、therewouldbenolivingthingsatallB、therichtopsoilcouldn'tbeholdback

　　C、heavyrainswouldcleanthetropics D、thelandwouldbecomemorefertile

　　( )2、Somedesertareas wereonce .

　　A、uselesslands B、verycold

　　C、landswith good solid D、covered with ice and snow

　　( )3、“Topsoil”means .

　　A、goodsoilonthesurface of the earth

　　B、dry soil in desert areas

　　C、soil which is useless

　　D、soilundertheroots of trees

　　( )4、 caused deserts.

　　A、Cuttingdowntrees

　　B、Never planting