单选题 -- Was the driving pleasant when you vacationed in country last summer?
-- No, it ______ for four days when we arrived, so the roads were very dirty.

【正确答案】 C
【答案解析】过去完成进行时表示在过去某一个时间或某一个动作之前一直在进行的动作。由题干知，在we arrived前雨已经下了四天了。故[C]正确。