—— 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
网友回答
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。