Yesterday it rained heavily when school was over. So we tay in our classroom.A. should B

问题补充：

Yesterday it rained heavily when school was over. So we tay in our classroom.

A. should B. must C. had to

答案：

解析：

试题分析:昨天放学时雨下的很大，所以我们只好呆在我们的教室里。A. should应该； B. must 必须；C. had to不得不，根据句意及时间状语yesterday（昨天）此题选B。