问题
选择题
I could have called you for help, but I ____ your number.
A．couldn’t remember
B．didn’t remember
C．should have remembered
D．hadn’t remembered
答案
答案：B
could have done 表示过去本可以做某事而没有，是一个与过去事实相反的虚拟语气，but后引出了一个过去事实,说明不能做的理由。故remember用一般过去时。