非谓语求帮解释啊

问题描述:

非谓语求帮解释啊
It showed that 49percent of the students (survey),form junior to senior high school in the city,suffered from some kinds of mental health problems .为什么survey那个空要填非谓语呢?

此句整句为宾语从句,It showed部分为主句,that是连词.连词后是一个句子,原则上英语的简单句只能有一个谓语或系动词,而这句话的谓语已经给了,就是suffered from,因此再出现动词的话,必须使用其非谓语形式.这样动词survey就必须用非谓语,从句子来看是做the students的定语,与被修饰的词之间是被动关系,因此用过去分词surveyed.