Trees are useful to men in three important ways:They p 1 them with wood and
Trees are useful to men in three important ways:They p 1 them with wood and other products,they give them shade,and they help to p 2 drought and floods.Unfortunately（不幸运地）,in many p 3 of the world,men don’t know that the third of these is the most important.In their eagerness（渴望） of making m 4 from trees,some people cut trees down in large n 5 reserves.And besides,they are usually too c 6 to plant and look after new trees,so the forests slowly b 7 smaller and smaller.This does not only mean that men will have fewer trees.The results are e 8 more serious:For where there are trees,their roots(根) prevent the rain from washing away the soil,but there are no trees,the rain falls on hard g 9 and flows away,causing f 10 and carrying away the rich top-soil（地表土）.When all the top-soil is gone,nothing remains（剩下） but death.