it for your help, I couldn’t have made any progress.
A. Had; not been
B. Should; not been
C. Did; not been
D. Not; been
网友回答
(答案→)A. Had; not been
B. Should; not been
C. Did; not been
D. Not; been
解析：考查虚拟语气。根据语境可知考查与过去事实相反的虚拟语气，故从句用had + v-ed，had it not been = if it had not been，故选A。