Farmers use different kinds of soil conservation methods to protect their land from damag

Farmers use different kinds of soil conservation methods to protect their land from damage by farming and the forces of nature . One important form of soil conservation is the use of windbreaks . Windbreaks are barriers formed by trees and other plants with many leaves . Farmers plant them in lines around their fields .
Windbreaks stop the wind from blowing soil away . They also keep the wind from destroying or damaging crops . They are very important for growing grains , such as wheat . There have been studies done on windbreaks in parts of West Africa , for example . These found that grain harvests can be twenty percent higher in fields protected by windbreaks pared to fields without such protection .
However , windbreaks seem to work best when they allow a little wind to pass through . If the wall of trees and plants stops wind pletely , then violent air motions will take place close to the ground . These motions will lift soil into the air where it will be blown away .
For this reason , a windbreaks is best if it has only sixty to eighty percent of the trees and plants needed to make a solid line . An easy role to remember is that windbreaks can protect areas up to ten times the height of the tallest trees in the windbreaks .
These should be at least two lines in each windbreak . One line should be large trees . The second line , right next to it , can be shorter trees and other plants with leaves . Locally grown trees and plants are best for windbreaks .
1.What is the best title for the passage?
A.Building a windbreak to protect soil
B.Building a windbreak to protect crops
C.Using a windbreak to improve grains
D.Using a windbreak to improve plants
2.In the fifth paragraph the author tells us windbreaks    .
A.do not work at all
B.do not stop wind fully
C.will not take place
D.will not allow wind to pass through
3.According to the passage , which of the following statement is wrong ?
A.Windbreaks are barriers .
B.Windbreaks can be used to make fences .
C.In general , there are two lines in all in every windbreak .
D.Windbreaks can protect areas .C