问题

Why you didn’t handed in your exercise paper?–Sorry, but I ____ that it should be turned in today
A:didn’t know
B:hadn’t known
C:haven’t known
D:don’t know
B:hadn’t known
C:haven’t known
D:don’t know
正确答案是:
同类题型
Had they known what was coming next, they________ second thoughts.
When______ what his plan for his summer holiday was, he got very excited.
—Why do you look so worried?— My MacBook Pro broke down and my paper ______ unfinished since.[ ]
Thank you for the flowers.—______. I thought they might cheer you up.