The ground is wet. Yes didnt you know? for the last 20 minutes.A. Its rainingB. It was

问题补充：

The ground is wet. Yes, didn you know? for the last 20 minutes.

A. Its raining

B. It was raining

C. Its been raining

D. It has rained

答案：

A. Its raining

B. It was raining

(答案→)C. Its been raining

D. It has rained

解析：时间状语for the last 20 minutes，表示的是过去的一段时间里完成的动作持续到现在并有可能继续下去，动词的时态应用现在完成进行时。故选C。