阅读理解。
In some places in North Africa, great cities once stood. There were gardens and trees and grass.
But now these places are like deserts. Scientists have begun to study this land to find out what
happened. Many of them think the land died when the trees were cut down. Trees help other plants
grow. Tree roots hold the earth in place. They stop the soil from being blown away. In forests, leaves
on the ground keep rainwater from running off. Trees near farmer protect growing plants from strong
winds.
Once there were hundreds of farms in the Southwestern United States. Then the farms turned into
fields of dry land, because few trees grow in the dry Southwest.
Now we try to save trees. In many forests, when a tree is cut down, a new tree is planted in its
place. We do not want the land to die.
1. What do trees possibly do?
A. Trees keep other plants away
B. Trees help other plants grow
C. Trees hold other plants down.
D. Trees destroy other plants.
2. Why did farms in the Southwestern United States turn into fields of dry land?
A.Because there have been few trees growing there.
B.Because people planted quite a few trees there.
C.Because many people moved there to make a living.
D.Because when a tree was cut down, a new tree was planted in its place.
3.The writer wants to tell us that______________.
A. farms are better than cities.
B. there are no deserts in Africa.
C. trees are important to the land.
D. Trees are quite important to American farms.
4.What's the best title of the passage?
A.Great cities in North Africa
B. Trees and land
C. Farms in the Southwestern United States
D. New deserts.