________ has been announced, we shall have our final exams next month．
A.That
B.As
C.It
D.What
网友回答
B解析此题考查as代替整个主句，引导非限制性定语从句的用法。如果选C项，应把从句改为：It has been announced that we shall have our final exams next month．如果选D项，此句应为：What has been announced is that we shall have our final exams next month．选项A中的that不能引导非限制性定语从句，故应排除。