问题
选择题
—— Do you still remember the day when we went to the Great Wall?
—— I can’t remember it well, but＿＿＿＿＿＿sometime last autumn?
A．might it be
B．could it have been
C．could it be
D．must it have been
答案
答案：B
could have done表示对过去发生情况的可能性推测。