If the weather had been better we could have had a picnic. But it all day.A. rainedB. ra

问题补充：

If the weather had been better, we could have had a picnic. But it all day.

A. rained

B. rains

C. has rained

D. is raining

答案：

(答案→)A. rained

B. rains

C. has rained

D. is raining

解析：从题干前部分句子的谓语动词结构（虚拟语气）可以看出是指过去某个时间已经下了整天的雨。所以应该用一般过去时态。该题解题关键要从题干前部分入手。if非真实条件句用的过去完成时，主句用would have done，我们可以看出这是与过去事实相反的虚拟语气。