Question

--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

Answer 1

D

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。