—Whyistheclassroomsodirty?—Sorry，sir. It       yesterda...

问题详情：

—Why is the classroom so dirty?

—Sorry，sir.  It        yesterday We forgot to do it.

      A．doesn’t clean                 B．didn’t clean       

     C．isn’t cleaned                   D．wasn’t cleaned

【回答】

D

知识点：动词语态

题型：选择题