If the Watergate Incident Nixon would not have resigned from the presidency.
A. did not occur
B. had not occurred
C. was not occurring
D. be circling
网友回答
A. did not occur
(答案→)B. had not occurred
C. was not occurring
D. be circling
解析：had not occurred表示对过去的虚拟，条件句中要用过去完成时，主句中要用should(would，could，might)+动词原形。