— Was the driving pleasant when you went to Mexico last summer? — No it ＿＿ for four days

问题补充：

— Was the driving pleasant when you went to Mexico last summer?

— No, it ＿＿ for four days when we arrived, so the roads were very muddy.

A. was raining

B. had been raining

C. would be raining

D. rained

答案：

A. was raining

(答案→)B. had been raining

C. would be raining

D. rained

解析：表示在过去某一动作之前一直在进行，并有可能继续下去的动作，要用过去完成进行时。