the article sugguests that when a person is under unusual stress he should be especially careful to have a well-balanced diet中为什么用is不用动词be

问题描述:

the article sugguests that when a person is under unusual stress he should be especially careful to have a well-balanced diet中为什么用is不用动词be

when的后面是个从句,从句就是另外一个独立完整的句子,表修饰.所以用is而不用be.