--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
网友回答
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。