--Must I clean the classroom now Miss Wang?--No you needn’t . It by Bill. A. is cleaning

问题补充：

--Must I clean the classroom now, Miss Wang?

--No, you needn’t . It by Bill.

A. is cleaning

B. should be clean

C. was cleaned

D. has been cleaned

答案：

A. is cleaning

B. should be clean

C. was cleaned

(答案→)D. has been cleaned

解析：句意：我必须现在打扫教室吗？不，不必。比尔已经打扫了。It和clean之间是被动系，用被动语态，而且强调对现在的影响，用现在完成时态的被动语态。选D。