if用于虚拟语气,主句用would,could,sould,might+动词原形,这4个词可以互换吗?

在引导虚拟语气条件句时,主句中一般总是用would不错,可以译为“就会”；有“可能会”、“也许会”之意时,用could,might较好；有“应该会”之意时用sould 较好.
If he had not been busy,he would/could/sould/might have helped you.他不忙的话,会/可能会/应该/也许会帮你忙的.