Unfortunately， in many parts of the world man has not realized that the third of these services is the most important. In his eagerness to draw quick profit from the trees， he has cut them down in large numbers， only to find that without them he has lost the best friends he had.
Two thousand years ago a rich and powerful country cut down its trees to build warships， with which to gain itself an empire. It gained the empire but， without its trees， its soil became hard and poor. When the empire fell to pieces， the country found itself faced by floods and starvation.
Even though a government realizes the importance of a plentiful supply of trees， it is difficult for it to persuade the villager to see this. The villager wants wood to cook his food with， and he can earn money by making charcoal or selling wood to the townsman. He is usually too lazy or too careless to plant and look after trees. So unless the government has a good system of control， or can educate the people， the forests will slowly disappear.
This does not only mean that the villagers sons and grandsons have fewer trees. The results are even more serious. For where there are trees their roots break the soil upallowing the rain to sink in and also hold the soil， thus preventing it being washed away easily， but where there are no trees， the soil becomes hard and poor. The rain falls on hard ground and flows away on the surface， causing floods and carrying away with it the rich topsoil， in which crops grow so well. When all the topsoil is gone， nothing remains but a worthless desert②.
译注
① ...and they help to prevent drought and floods.
它们有助于防止干旱和水灾。
③ When all the topsoil is gone， nothing remains but a worthless desert.
当表层土流失后，就只剩下一片无用的沙漠。
根据文章内容，选择正确答案：
1. The purpose that the writer wrote this article for is .
A. to tell people that trees are very useful to man
B. to warn people not to cut down trees any more
C. to warn that man mustnt destroy forests any more
D. to explain how trees help to prevent drought and floods
2. In the writers opinion， ， or the forests slowly disappear.
A. measure must be taken
B. people shouldnt draw benefit from the tree
C. government must realize the serious results
D. unless trees never be cut down
3. According to the article we know it is to prevent the forests from slowly disappearing.
A. necessary but impossible
B. necessary but difficult
C. impossible and unimportant
D. difficult and impossible
4. In the last two paragraphs the writer wanted to make it clear that .
A. where there are no trees， the soil becomes hard and poor
B. where there are many trees， there are fewer floods
C. where there are no trees， the land might become desert slowly
D. floods will make the land become desert
完形填空
Passage D
Is the world really going mad？ The other day I was sitting in a small restaurant 1a quiet drink and a talk with a few friends， when it suddenly 2 me that almost everyone in the restaurant was smoking. It wasnt long3 the whole room was filled with smoke. I asked with an apology for permission to open a window to stop myself4 ！
Nowadays air pollution is something that we hardly question any more①. However， I still cant walk down the streets in any of the big cities without5 that people are suffering from the air pollution. It is time for the government departments the world over to introduce emission （废气排出） controls on all cars6 the public transport system （公共交通系统） to encourage people to7 their cars at home. A friend of mine takes flying each morning and it really makes him8 when he climbs above the smog layer and looks down9 it and thinks： “Im breathing that！” This kind of10 results from the bad management of resources. Waste things can，11 should be treated properly.
House building， road construction and industrial development are all earthmoving （or earthreducing） operations and can change the balances of12 created over millions of years. I would like to13 serious studies done on all these main words before they are built. Also， there should be14 national parks set up to keep the most beautiful parts of our countries in their natural15.
译注
① Nowadays air pollution is something that we hardly question any more.
目前，空气污染是我们几乎无需质疑的问题。
根据文章内容，选择正确答案：
1. A. have
B. had
C. having