he would have finished his college education,but he had to quit and find a job to support family句中为什么用had不用would have

he would have finished his college education,but he had to quit and find a job to support family句中为什么用had不用would have
he would have finished his college education,but he had to quit and find a job to support family
句中为什么用had不用would have

he would have finished his college education,but he had to quit and find a job to support family句中为什么用had不用would have
这句话涉及虚拟语气用法.过去时间段的虚拟语气,句式 ：主句谓语 would/should/could/ have +过去分词 ,从句谓语 had+过去分词.而从句有时候是可以省略的.
这句话补充完整应是 If he had money,he would have finished his college education,but he had to quit and find a job to support family.
注意 but 转折后跟的是 had to do 用法,而不是had done哦.换言之 but 是过去式时态,与虚拟语气无关.
这句话可以这样理（如果有足够的钱）他本应该完成学业,但现在不得不退学找工作赚钱养家.

因为这句是虚拟语气，意思是“他原本可以完成他的大学学业”，其实并没有完成，后半句就是这个意思。