—I’m sorry,but there’s no smoking on this flight.
—Oh,I that.Sorry, I won’t again.
A. don’t know
B. didn’t know
C. won’t know
D. haven’t known
网友回答
A. don’t know
(答案→)B. didn’t know
C. won’t know
D. haven’t known
解析：本题考查动词时态。根据句意“在(说话)之前不知道飞机上不能抽烟” 可知，这是对过去事实的叙述，所以用一般过去时。