Our classroom is very clean. Do you know who＿＿＿cleaned it? A. was it thatB. it was that C.

问题补充：

Our classroom is very clean. Do you know who＿＿＿cleaned it?

A. was it that

B. it was that

C. was it who

D. he was

答案：

A. was it that

(答案→)B. it was that

C. was it who

D. he was

解析：who引导的从句是强调句型，在句中作宾语,用陈述语序。