Thehazeorsmogwassoseriousthatthewinterrunning

问题详情：

 The haze or smog was so serious that the winter running _________. Some students complained as they ran.

A. could have cancelled       B. should have cancelled

C. must have been cancelled   D. ought to have been cancelled

【回答】

D

知识点：虚拟语气与情态动词

题型：选择题