It was Jane I saw in the library this morning.A. thatB. whichC. whatD. when

问题补充：

It was Jane I saw in the library this morning.

A. that

B. which

C. what

D. when

答案：

(答案→)A. that

B. which

C. what

D. when

解析：考查强调句：强调句的结构是：It is/was+强调部分+that+其余部分。判断是否是强调句的方法是去掉强调结构，如果句子仍然成立就是强调句：这句话去掉强调结构句子是：I saw Jane in the library this morning.所以是强调句，强调的是宾语，选A。