Question

but for,without,在虚拟语气里怎么用，就是从句主句谓语动词用什么

Answer 1

句中but for, without， but这些词，是一种含蓄的虚拟语气，也是解题的关键点，即见到他们你也要想到这题多半是考虚拟语气的。它们只是种标志，这时只有主句，没有从句，（不要和if类的虚拟混淆）
主句+would do(表对现在或者将来的虚拟)
主句+would have done（表对过去的虚拟）

例如：Without your timely help, we couldn't have finished our task. 如果没有你的及时帮助，我们可能完成不了任务。

Answer 2

一般要根据句子中的时间状语或者句子意思来判断吧。
but for/without sth, 主句+would do(表对现在或者将来的虚拟)
主句+would have done（表对过去的虚拟）

Answer 3

含蓄条件句中虚拟语气的应用
But for/without…，……
……, otherwise/or…
……, but/though….
例1：But for your help, I _____ the work in time.
A. did not finish B. could not finish
A. will not finish D. would not have finished
例2：Without electricity, human life _____ quite different today.
A. is B. will be C. would have been D. would be

例3：He was very busy yesterday; otherwise he_____ to the meeting.
A. would have come B. would come C. could come D. had come

例4：We would have made a lot of money, but we halfway
A. gave up B. had given up C.would give up D. were to give up