英语的动词有三种语气形式，即陈述语气、祈使语气和虚拟语气。虚拟语气是谓语动词的一种特殊形式，用来表达假设、主观愿望、猜测、建议、可能或空想等非真实情况。
第一类
虚拟语气在条件句中的用法：
条件句有真实条件句和虚拟条件句两种。真实条件句所表示的假设是有可能发生的，此时主句不用虚拟语气；而虚拟条件句则表示一种假想，与事实相反或不大可能会发生，此时用虚拟语气。
第二类
使用虚拟语气的常见结构或从句：
1.*wish与hope接宾语从句的区别在于：hope表示一般可以实现的希望，宾语从句用陈述语气。wish表示很难或不大可能实现的希望,宾语从句用虚拟语气。
2.ifonly与Iwish一样，也用于表示与事实相反的愿望，其后所虚拟语气的时态与wish后所接时态的情况相同
3.lwouldrather后句子用虚拟语气只分现在和过去
在wouldrather,wouldsooner,wouldjustassoon后的that从句中,句子谓语习惯上要用虚拟语气，表示"宁愿做什么"
4.lasif(though)从句用虚拟语气
以asif(asthough)引导的方式状语从句或表语从句，有时用虚拟语气,则与wish用法相同
点击查看：高考英语虚拟语气怎么复习
第三类
从句中should+动词原形，should可省略
1.在lest，forfearthat(以免),incase(以防)引导的目的状语从句中的虚拟语气
Shewalkedquietlylestshe(should)wakeupherroommates.她走得很轻以免吵醒她的室友。
2.表应当做值得做一类动词后的宾语从句
建议advise,suggest,propose,recommend命令order,command
请求ask,demand,require,request指示direct
督促urge提议move,vote
希望desire坚持insist
打算intend安排arrange
3.order,suggestion,idea,plan,proposal,advice,demand等名词后的表语从句或同位语从句
Oursuggestionisthatyou（should）bethefirsttogo．我们的建议是你应该第一个去。
4.*advice,agreement,command,decision,decree,demand,determination,indication,insistence,order,preference,proposal,request,requirement,stipulation,suggestion,idea,plan,order
第四类
It’stime后的从句用虚拟语气
从句谓语通常用过去式表示(早)该干某事了
*有时也用过去进行时或“should+动词原形”(较少见，且should不能省略)
第五类
表示祝愿话语中也可以用虚拟语气。
第六类
在少数句型中，谓语用虚拟语气。
1）由that引导的句子（表示愿望或沮丧情绪）
2）由wouldthat引导的句子（表示但愿）
3）由tothink引导的句子（表示没想到）
1.(北京卷)34.We___backinthehotelnowifyoudidn’tlosethemap.
A.areB.wereC.willbeD.wouldbe
2.(福建卷)32.nomoderntelecommunications,wewouldhavetowaitforweekstogetnewsfromaroundtheworld.
A.WerethereB.HadtherebeenC.IfthereareD.Iftherehavebeen3.(湖南卷)22.IfMr.Dewey__present,hewouldhaveofferedanypossibleassistancetothepeoplethere.
A.wereB.hadbeenC.shouldbeD.was4.(陕西卷)23.Wewouldratherourdaughter_athomewithus,butitisherchoice,and
sheisnotachildanylonger.
A.wouldstayB.hasstayedC.stayedD.stay
5.(天津卷)15._themorningtrain,hewouldnothavebeenlateforthemeeting.
A.DidhecatchB.shouldbecatchC.hashecaughtD.Hadhecaught
6.(浙江卷)16.Theywereabroadduringthemonthswhenwewerecarryingouttheinvestigation,orthey___toourhelp.
A.wouldhavecomeB.couldcomeC.havecomeD.hadcome7.(重庆卷)13.ItwasJohnwhobrokethewindow.WhyareyoutalkingtomeasifI__it
A.haddoneB.havedoneC.didD.amdoing
8.(重庆)29.-Itrainedcatsanddogsthismorning.I’mgladwetookanumbrella.-Yeah,wewouldhavegotwetalloverifwe___
9.(安徽)28.I___tomycousin’sbirthdaypartylastnight,butIwasnotavailableA.wentB.hadgoneC.wouldgoD.wouldhavegone
10.(辽宁)31.Harryisfeelinguncomfortable.He___toomuchatthepartylastnight.
A.coulddrinkB.shoulddrinkC.wouldhavedrunkD.musthavedrunk11(陕西)21.Thechildren___lostinthewoods;otherwise,theywouldhavebeenatthe
lakesidecampasscheduled.
A.musthavegotB.mustgetC.shouldhavegotD.shouldget12.(四川)5.—Whyareyoureyessored
Youhavesleptwelllastnight.—Yeah,Istayeduplatewritingareport.A.can’tB.mustn’tC.needn’tD.won’t13.(北京)34.Ifwe___atableearlier,wecouldn’tbestandinghereinaqueue.A.havebookedB.bookedC.bookD.hadbooked
14,(福建)30.----DoyouthinkGeorgehaspassedthedrivingtest----No.Ifso,he____hiscartoourcollegeyesterday.
A.woulddriveB.droveC.wouldhavedrivenD.haddriven15.(江苏)30.IshouldnothavelaughedifI___youwereserious.A.thoughtB.wouldthinkC.hadthoughtD.havethought
16.(陕西)12.Mymomsuggeststhatwe___eatoutforachangethisweekend.A.shouldB.mightC.couldD.would17.(天津)14.IfhehadspentmoretimepracticingspeakingEnglishbefore,he___abletospeakitmuchbetternow.
A.willbeB.wouldbeC.hasbeenD.wouldhavebeen
18.(浙江)8.Eyedoctorsrecommendthatachild’sfirsteyeexam___attheageofsixmonthsold.
A.wasB.beC.wereD.is
19.(浙江)Hadtheyknownwhatwascomingnext,they_secondthoughts.
A.mayhaveB.couldhaveC.musthavehadD.mighthavehad
20.(天津)WewouldhavecalledataxiyesterdayifHaroldusaridehomeA.didn’tofferB.wouldn’tofferC.hasn’tofferedD.hadn’toffered
A.livesB.wouldliveC.havingaskedD.weretolive
24.(湖南)Sorry,Iamtoobusynow,ifItime,Iwouldcertainlygoforanoutingwithyou.
27.(北京)We___thedifficultytogether,butwhydidn’tyoutellme
A.shouldfaceB.mightfaceC.couldhavefacedD.musthavefaced28.(北京)Don’thandlethevaseasifit____madeofsteel.
A.isB.wereC.hasbeenD.hadbeen
29.(福建)Welostourwayinthatsmallvillage,otherwisewe_moreplacesofinterestyesterday.