首先,要理解虚拟语气的定义:虚拟语气是一种不肯定的语气或者是假设的语气,比如if(如果,假如),asif(就像,只是像但实际上不是).
其次,要分清楚虚拟语气的几种常见类型:
一.If引导的非真实条件句(注意if引导的可以实现的条件,称为真实条件句)
If从句,主句
(将来)1.过去式(be只能用were),would/should/could/might+V原
2.wereto+V原,would/should/could/might+V原
3.should+V原,would/should/could/might+V原
Ifthereshouldbenoair,therewouldbenolivingthings.
(现在)过去式(be只能用were),would/should/could/might+V原
IfIwereabird,Iwouldflyeverywhere.
(过去)haddone,would/should/could/might+havedone
Ifwehadstartedearlier,weshouldnothavemissedthetrain.
(当然,有时候是主句在前,if从句在后,规则是一样的.)
二.从句中的虚拟语气
1.表示愿望,建议,命令,要求等的宾语从句中,要用“(should)+动词原形”,这些词有:
wish,suggest,order,demand,propose,command,request,recommend,require,decide,insist,desire,urge,suggestion,proposal,plan,motion,recommendation,demand,order,desire,request,requirement,insistence,advice,decision,obligatory.
Ourteachersuggestedthatwe(should)givetheoldmansomehelp.
2.在Itis/was+某些形容词+that从句的句型中,that从句中的谓语动词常用虚拟语气,即“should+动词原形”.这些形容词有:
important,necessary,essential,imperative,natural,strange,advisable,desirable,possible,probable,astonishing,surprising,desired,suggested,requested,recommended,ordered,proposed,decided,moved等
Itisimportantthatweshouldgetthereontime.
3.在“Itis(about/high)time+that(从句)”中,谓语动词常用过去式表表示虚拟语气
ItishightimethatpeoplelearntEnglish.
4.在“asif/asthough”引导的状语从句中,谓语动词与wish的宾语从句的虚拟形式相同.
Itseemsasthoughitwerealreadyspring.
三.省略if的非真实条件句
if省去,将助动词.情态动词.be或have放在句首形成部分倒装.
IfIwereyou,Iwouldnotdothosestupidthings.
=WereIyou,Iwouldnotdothosestupidthings.
Ifhehadknownaboutthis,hewouldhavebeenverysad.
=Hadheknownaboutthis,hewouldhavebeenverysad.
四.含蓄虚拟语气
有时假设的情况并不以条件从句表示出来,而是暗含在上下文中,比如通过介词短语来表示.Butfor(要不是)without(没有...的话)otherwise(否则)
Butforyouradvice,Icouldnothavedoneitsosuccessfully.
Thechangecouldnothavetakenplacewithouttheopen-doorpolicy.
Iwassobusythen,Otherwise,Iwouldhavetoldhimtheanswer.
五.错综时间虚拟句
非真实条件句中主句和从句的谓语动词所指时间有时可能指不同的时间,这时要根据上下文的意思采用不同的谓语动词形式.
IfIwereyou,Iwouldhavetakenhisadvice.(从句指现在,主句指过去)
IfIhadtakenmyraincoatwithmethismorning,Iwouldnotbewetnow.(从句指过去,主句指现在).
六.用在ifonly引起的感叹句中.
Ifonlythedriverdidn’tdrivesofast!