题目内容：

trees can prevent the water from washing the earth away该同义句
trees can _________ the water from________ the earth away

优质解答

Trees can prevent the water from washing the earth away.
= Trees can (stop) the water from (washing) the earth away.
= Trees can (keep) the water from (washing) the earth away.
注：stop/keep/prevent...from doing sth,意思都是“阻止...做某事”.