About seventy percent of the earth with water.A. is coveringB. is covered C. are coveringD

问题补充：

About seventy percent of the earth with water.

A. is covering

B. is covered

C. are covering

D. are covered

答案：

A. is covering

(答案→)B. is covered

C. are covering

D. are covered

解析：句意：地球大约70%的部分被水覆盖着。the earth做主语为不可数名词，所以谓语动词用单数形式，地球与水覆盖应该是动宾关系，所以用被动语态；故选B。