题目内容
Different kinds of soil conservation methods are used by farmers 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 (屏障) 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. They found that grain harvests can be twenty percent higher in fields protected by windbreaks compared 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 completely, 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 windbreak is best if it has only sixty to eighty percent of the trees and plants needed to make a solid line.
There 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 a windbreak according to the passage?
A. A windbreak is a concrete wall to prevent the strong winds.
B. A windbreak is a wood with different kinds of trees.
C. A windbreak is a wall of trees to hold soil in place.
D. A windbreak is a wall of wind to fight wind from the opposite way.
2.When can windbreaks be most effective?
A. The trees are planted one by one.
B. The trees and plants grow in a line.
C. The trees grow as high as they can.
D. Windbreaks allow a little wind to blow through.
3.Which of the following statements is NOT true?
A. A windbreak is one of the best forms of soil conversation.
B. A windbreak is very good for growing grains such as wheat.
C. One line of trees is enough for soil protection.
D. Locally grown trees and plants are the top choice for a windbreak.
