But for their help we the program in time．A. can not finishB. will not finishC. had not

问题补充：

But for their help, we the program in time．

A. can not finish

B. will not finish

C. had not finished

D. could not have finished

答案：

A. can not finish

B. will not finish

C. had not finished

(答案→)D. could not have finished

解析：考查虚拟语气。But for“要不是......”，相当于if虚拟条件句，与过去事实相反，主句用would/should/could have done。句意“要不是他们的帮助，我们不可能及时完成计划。”故选D。