Many teachers believe it----------(necessary) to give students tests every week.
问题描述：
Many teachers believe it----------(necessary) to give students tests every week.
要加be动词吗?
答
可以加,也可以不加,都是对的.
加is,则believe 后面是个宾语从句,不加则是个简单句,it做形式宾语,真正的宾语是后面的不定式to give students tests every week.
一些动词,如believe/think/find/suppose/feel/等,believe/think/find/suppose/feel it +adj+to do sth=believe/think/find/suppose/feel/ +(that)+it be+adj+to do sth.