If you want your land to keep fertile, you must try to stop soil from being carried away by water or wind. When soil is taken away by flowing water or blowing winds we call it soil erosion. Ways have been found to stop soil erosion, and this is known as soil conservation. One way of stopping soil erosion is to grow small plants such as grass. These plants are referred to a cover crops, whose roots hold the soil tightly together. The rain water can not wash away the soil. When trees and tall bushes are planted at the edges of an open field, soil erosion by strong winds can not take place. The trees and bushes, which act as a very big and firm wall, protect the open land from the winds. The way to stoop soil erosion on slopes is to build terraces on the slope of hillside and mountainside. When the slope of a hillside is cut into “step”, water carrying soil can not run straight down the terraces, which are used to slow down the speed of the flowing water containing much soil in it. In this way most of the soil in the water is left behind on the terraces, much soil in it.
What takes place in soil erosion?

A．Flood happens to the fertile land

B．A large quantity of the soil loses away gradually.

C．Terraces are built on the slope of hillside or mountainside.

D．Plants are grown to protect the open land

“Cover crops” in this passage means _________.?
A. grass        B. trees and bushes     C. plants life and an area
E.   covering plants that produce grain or vegetables
Besides growing small plants, another method to fight against soil erosion is to ___________.

A．build terraces

B．build walls

C．plant trees

D．plant tall bushes

According to the passage, trees and tall bushes are planted around an open field ________________.

A．because their roots hold soil tightly

B．to stop soil from being blown away by winds.

C．Because soil erosion causes terrible damages to crops

D．To keep the balance of nature

Which of the following is the best title of the passage?

A．What Causes Soil Erosion

B．The Importance of Erosion

C．Rain Erosion and Wind Erosion

D．Erosion and the Way of Tight against Erosion