It was when she was sleeping in her bedroom a thief broke into the house.A. whichB. thatC

问题补充：

It was when she was sleeping in her bedroom a thief broke into the house.

A. which

B. that

C. where

D. than

答案：

A. which

(答案→)B. that

C. where

D. than

解析：句子去掉It was和之后，剩下a thief broke into the house when she was sleeping in her bedroom.是一个完整句子，所以原句是强调句型，选B。