The number of senior high school students is increasing...The number of senior high school students is increasing,as is mentioned above.请问这个句子后面的部分 as is mentioned above 为什么没有it?

问题描述:

The number of senior high school students is increasing...
The number of senior high school students is increasing,as is mentioned above.
请问这个句子后面的部分 as is mentioned above 为什么没有it?

这里是as单独引导定语从句,先行词可以是一个词,也可以是一个句子或短语.例如: (1) She is late, as is often the case.她迟到了,这是经常的事.(先行词是整个主句) (2) To shut your eyes to facts, as many of yo...