—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
网友回答
A. doesn’t clean
B. didn’t clean
C. isn’t cleaned
(答案→)D. wasn’t cleaned
解析：句意：教室为什么这么脏？——抱歉，老师。昨天没有打扫，我们忘记做了。结合语境可知下文描述的是过去的状态，故用一般过去时态，主语是动作对象，故用被动语态。选D。