虚拟语气在英语中应使用什么时态

虚拟语气用在一般现在时，

从句IF+S+一般过去时,主句S+SHOULD/WOULD+V

例子：IfIstayedinthatschool,Iwouldpasstheexam.

虚拟语气用在一般过去时，

从句IF+S+过去完成时，主句S+SHOULD/WOULDhavedone

例子：Ifyouhadbeenhereyesterday,youwouldhavemethim.

虚拟语气用在一般将来时，

从句IF+S+was/weregoingtodo,主句S+SHOULD/WOULD+V

例子:ifitwasgoingtorain,wewouldn'tgoonapicnicthisSunday.