问题补充：
she is not so cheerfulshe used to be?
A. How it is that；as
B. How is it that；as
C. Is it why；that
D. Why is it that；what
答案：
A. How it is that；as
(答案→)B. How is it that；as
C. Is it why；that
D. Why is it that；what
解析：考查强调句的特殊问句和比较级：强调句的特殊疑问句式是：特殊疑问词+is/was it that+其他部分？句意：为什么（怎么）她不像以前一样那么高兴，像…一样 === as ...as（陈述句） === so ...as（否定句）,选项D中的what不能和前面的so构成同级比较，因此B项正确。
