i would have come earlier,but i __you were waiting.

题目

i would have come earlier,but i __you were waiting.
为什么选didn't know不选hadn't know?

答案

didn't know
我本该早到的,可我（刚才）不知道你正在等.
you were waiting,这个动作,见了面之后,就知道了,所以不知道这个动作,是刚才的,过去的.
所以要用：didn't know,现在已经知道了.