单项选择题

When there is a heavy rain, trees can help to prevent floods, as they can ______

A．keep rain from falling down to soft ground
B．cause the soil to allow rainwater to sink in
C．make the topsoil stick together
D．prevent the soil from being washed away

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热门试题

单项选择题

According to the passage, trees are useful to man mainly in three ways, the most important of which is that they can ______

A．keep him from the hot sunshine
B．prevent him from floods
C．make him draw quick profit from them
D．help him to keep from the attack of drought and floods

单项选择题

Two thousand years ago, a rich and powerful country met with floods and starvation because of ______

A．the soil of the country became barren
B．its empire fell
C．it cut too many trees down
D．the conquered land within its empire was poor and barren