The whole building burned down, but the heavy rain .
A. might have; would help
B. could have been; helped
C. must have; helped
D. should have been; was helping
网友回答
A. might have; would help
(答案→)B. could have been; helped
C. must have; helped
D. should have been; was helping
解析：本题前半部分是虚拟，“本来会烧毁的”，后半部分是陈述语气，表示实际情况，而且是过去发生的事情，用could +现在完成时和过去时。