问题补充：
--Was the driving pleasant when you vocationed in Mexico last summer?
----No, it for four days when we arrived, so that the roads were very muddy.
A. was raining
B. had been raining
C. would be raining
D. have rained
答案：
A. was raining
(答案→)B. had been raining
C. would be raining
D. have rained
解析：这句意是:当我们到达时, 已下了四天的雨, 所以路面非常泥泞.,所以这里要选B项.
