we have been told that in no cases__our friends during office hours.A.may we call B.did we case
问题描述：
we have been told that in no cases__our friends during office hours.
A.may we call B.did we case
答
A in case后面的时态是一般现在时，或情态动词，一般不加过去时
答
选A.意思是我们决不可以上班时间给朋友打电话
B是过去式,表示的是过去,所以不合题意