问题补充:
—Why is the classroom so dirty?
—Sorry,sir. Ityesterday, We forgot to do it.
A. doesn’t clean
B. didn’t clean
C. isn’t cleaned
D. wasn’t cleaned
答案:
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。