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 . 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.
1.__________ 2.__________ 3.__________ 4.__________ 5.__________
6.__________ 7.__________ 8.__________ 9.__________ 10.__________
1.provide 2.prevent 3.part 4.money 5. numbers 6.careless 7.become 8.even 9.ground 10.floods