I could have helped the old man yesterday morning.
A. did I e
B. if I came
C. had I e
D. if I should e
网友回答
A. did I e
B. if I came
(答案→)C. had I e
D. if I should e
解析：句意:如果我昨天来的话我就能帮助那位老人。这是省略if的条件状语从句，并且是虚拟语气，从句中有过去的时间状语，所以对过去的虚拟谓语应该用had done，省略if时，把had提到主语的前面，故选C。