Don’t you know that Australia was as a matter of fact used to be a nation of prisoners!

问题补充：

Don’t you know that Australia was, as a matter of fact, used to be a nation of prisoners!

A. where

B. what

C. which

D. that

答案：

A. where

(答案→)B. what

C. which

D. that

解析：句意：难道你不知道澳大利亚实际上是一个囚犯的国家吗?这里是what引导的表语从句，what在从句中作主语，where不能在表语从句中作主语，which在定语从句中可以作主语，that在表语从句中不作成分，故选B。