I didn’t know your telephone number; otherwise, I you long ago.
A. had rung
B. have rung
C. would have rung
D. would ring
网友回答
A. had rung
B. have rung
(答案→)C. would have rung
D. would ring
解析：考查隐含的虚拟语气：句意：--我不知道你的电话号码，否则，我早就会给你打电话了。这里的Otherwise相当于=if I had known your phone number.，所以主句用would have done，选C。