I sooner but I didn’t know that they were waiting for me.
A. had e
B. was ing
C. would e
D. would have e
网友回答
A. had e
B. was ing
C. would e
(答案→)D. would have e
解析：考查虚拟语气的用法。句意为“我本来可以早点来，但我真不知道他们在等我。”but I didn’t know表示了过去时间，因此前句是对过去的虚拟，用主语+should / would / could / might + have done表达，故选D。