20. raining hard for 3 hours without stopping.21.A. It is　　　B. It was　　　C. It has beenD. I

问题补充：

20. raining hard for 3 hours without stopping.

21.

A. It is

B. It was

C. It has been

D. It had been

答案：

A. It is

B. It was

(答案→)C. It has been

D. It had been

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