It last night., because the ground is all wet
A. should rain
B. should have rained
C. must rain
D. must have rained
网友回答
A. should rain
B. should have rained
C. must rain
(答案→)D. must have rained
解析：考察情态动词的推测性用法。根据last night可知，本句是对过去动作的推测，即排除AC, B意为本应当下雨（而实际上没有下雨），D，意为一定下雨了。
句意为昨天晚上肯定下雨了，因为地上都湿了。