your letter, I would have started off two days ago.
A. If I received
B. Should I receive
C. If I could have received
D. Had I received
网友回答
A. If I received
B. Should I receive
C. If I could have received
(答案→)D. Had I received
解析：考查虚拟语气，从后面的主句的时态可知if条件句要用和过去相反的虚拟语气，if的非真实条件句可以省略if，提前had，were，should，Had I received=if I had received，选D