70 percent of the surface ________ water.

A.is covered with

B.cover with

C.are covered with

D.covers with

答案及解析： A

解析：

【巧解导析】“百分数+of+不可数名词”，谓语应用单数动词．也就是说，百分数作主语时谓语动词要看它后面的名词是不可数名词还是可数名词复数．如果是不可数名词则用单数动词，如果是可数名词复数则用复数动词．