【题目】Someone ____the tap on, for the water was running over and flooding the bathroom.
A. could leave
B. must have left
C. might leave
D. should have left
在线课程【答案】B
【解析】
考查情态动词+完成式。句意：一定是有人没关水龙头，因为水溢出来淹了浴室。must have done表示对过去是清有把握的坑定推测，意思是“一定是做某事了”，故选B。