题目内容：

Is your brother old enough to be a member of our association?
中为什么要加be?不能省略吗?

优质解答

to be a member ...
因为前面用了不定式,而不定式的后面是需要跟动词的.这里的动词由系动词担当.表示"作...成..为...是..."等意思,故be不可省略.