She looks sad. Could you please tell me ____ that prevents her from being as happy as before?
A.what it is
B.it is what
C.how it is
D.it is how
网友回答
A解析主要测试宾语从句。只不过把宾语从句的测试放到强调句型中来测试，首先按照强调句型的判断方法：把It is···that去掉，则很容易地看出what引导的宾语从句，而且what在从句prevents her from being as happy as before中充当主语。所以选择A最佳。译文：她看起来不高兴。你能告诉我究竟是什么让她没有以前那么高兴了吗？