题干

_______ not easy _______ people ______ clean groundwater.
A.It's , for,  in findingB.It, for , in finding
C.It , for , to find.D.It's , for, to find
上一题 下一题 0.65难度 单选题 更新时间:2018-11-18 09:48:07

答案(点此获取答案解析)