问题
选择题
________ is mentioned above that the number of the students in senior high school is increasing.
A．Which
B．It
C．That
D．As
答案
答案：B
题目分析：考查it做形式主语：句意：上面提到的是高中的学生数量在增加。It是形式主语，that引导的是主语从句，which和as应该引导非限制性定语从句，that引导的是主语从句，选B。