if only引导句子的时态问题

问题描述:

if only引导句子的时态问题

要用虚拟语气,if only+did 对现在的虚拟
if only+could/might/would 对将来的虚拟
if only+had done 对过去的虚拟主句呢主句分别是:I would do.... I would do....... I would have done(过去)/ I would do.....(现在)