问题
选择题
It has been proved _______ violence on television has a bad effect on children.
A．whether
B．because
C．what
D．that
答案
答案：D
It has been proved that … 意为“已经证明”。It为形式主语，真正的主语为that引导的从句。句意为：事实证明，暴力电视节日对儿童有不良影响。