问题
选择题
--Excuse me, I don't think you can smoke here.
---Really sorry. I ______ this is a non-smoking room.
A．didn't know
B．don't know
C．have no idea
D．haven't known
答案
答案：A
题目分析：考查时态：句子的意思是：——打扰一下，先生，这是禁烟室。——抱歉，我不知道这是禁烟室。“我不知道这是禁烟室”应该是发生在过去的事情，所以使用一般过去时即可。选A。
点评：对于时态的考查要放个在具体的语境中，不能孤立，。