is mentioned above,the number of the students in senior

题目

is mentioned above,the number of the students in senior
is mentioned above,the number of the students in senior high schools is increasing
a that b as c which d it

答案

选择B 非限制性定语从句,指代下文全部内容,“如上所述,高中生的人数在增长”
如果选D it的话需要写成 It is mentioned that the number of the .