Thinking that you know in fact you don’t is a serious mistake.A. what　B. that　C. when　D.

问题补充：

Thinking that you know in fact you don’t is a serious mistake.

A. what

B. that

C. when

D. however

答案：

(答案→)A. what

B. that

C. when

D. however

解析：本题考查学生对主语从句和宾语从句的穿插理解。在that you know in fact you don’t宾语从句中缺少一个能承前启后的联系；同时又作know和you don’t know的宾语,因此只有A项,what疑问代词最充分。