题目内容：

-I just have no idea ( ) that made liu huan such a famous singer.
-Certainly his wonderful singing skill and ability.
A.it was what
B.what he did
C.how he did
D.what it was

优质解答

D
no idea 后面句子构成idea的同位语.这个同位语又是由what引导的主语从句担当的.在这个主语从句里面又包含了强调句型,确实够复杂的.
把it was that 去掉还原看, what made liu huan such a famous singer这是一个完整句子,并且构成idea同位语.
what 可引导主语从句和宾语从句,就这两种.