If-和whether的区别-(含--讲解+习题+答案)

If和whether的区别if和whether都可译为\是否\,二者引导宾语从句时通常可以互相替换,口语中多用if代替whether.例如：Askif/whetherheplanstocometothemeeting.而以下几种情况中,只能用whether:1.强调两方面的选择,特别是句中有ornot时.如：Letmeknowwhetheryoucancomeornot.2.宾语从句前置时.如：Whetherthisistrue,Ican\'tsay.3.引导主语、表语、同位语从句时.如：Whetherthefootballgamewillbeplayeddependsontheweather.（主语从句）Thequestioniswhetherhecandoit.（表语从句）Thequestionwhetherweshouldgowiththemmustbedecidedatonce.（同位语从句）4.在介词之后作介词的宾语时.如：Ihaven\'tsettledthequestionofwhetherI\'llgobackhome.5.在不定式前与不定式一起组成词组时.如：Whethertogoorstayisstillaquestion.6.在discuss,decide等动词后作宾语时.如：Wediscussedwhetherweshouldgotherebyplane.值得注意的是：if还可以引导条件状语从句,是\假如；如果\之意,而whether可以引导让步状语从句,是\不管；无论\之意.如：Ifyouaskhim,hewillhelpyou.Ishallgo,whetheryoucomewithmeorstayathome.一、if或whether引导宾语从句时,作“是否”讲,常放在动词ask、see、say、know和findout等后面.一般情况下,两者常可换用,在口语中多用if.如：例1Nobodyknowswhether(if)itwillraintomorrow.没有人知道明天是否下雨.例2Lucyaskedwhether(if)theyhadacottonsweater.露西问他们是否有棉制的羊毛衣.二、if或whether引导宾语从句时,要注意三个方面,即连词、语序和时态.1if或whether不能和that或其它连词（副词）同时使用,也不能省去.如：例3我不知道他今天是否会来.[误]Idon’tknowthatif(whether)hewillcomeheretoday.[正]Idon’tknowif(whether)hewillcomeheretoday.例4他走过来看看猫是否出了毛病.误]Hecametoseewhatif(whether)therewaswrongwithhiscat.[正]Hecametoseeif(whether)therewaswrongwithhiscat.2if或whether引导的宾语从句时,虽具有疑问意义,但从句语序应用陈述句语序.如：例5Didyouknowthewaytothehospital?Theoldwomanaskedme.Theoldwomanaskedme.if(whether)Iknewthewaytothehospital.老妇人问我是否知道去医院的路.3if或whether引导的宾语从句应和主句的时态保持一致.即主句为一般现在时,从句用任一种时态；主句为一般过去时,从句则用过去时中的任一种时态.如：例6Idon’tknowif(whether)hehascomehere.我不知道他是否来过这儿.例7Tomaskedif(whether)Ihadreadthebook.汤姆问我是否看过这本书.三、if和whether的区别：1在动词不定式之前只能用whether.如：例8Ican’tdecidewhethertostay.我不能决定是否留下.2在whether……ornot的固定搭配中.如：例9Iwanttoknowwhetherit’sgoodnewsornot.我想知道是否是好消息.3在介词后,只能用whether.如：例10Hisfatherisworriedaboutwhetherhelosehiswork.他的父亲担心是否会失去工作.4宾语从句放在句首表示强调时,只能用whether.如：例11Whethertheycanfinishtheworkontimeisstillaproblem.他们是否能准时完成这项工作还是个问题.5用if会引起歧义时,只用whether.如：例12Couldyoutellmeifyouknowtheanswer?这句话有两种意思：“你能告诉我是否知道答案吗?”或“如果你知道答案,请告诉我,好吗?”.如用whether可避免歧义.if和whether专题1)Idon'tcare__________yourcarbreaksdownornot.2)Thisdependsupon_________wearedeterminedtodoit.3)Itdependson_________heisready.4)Iamnotinterestedin_________you'llcomeornot.5)Wehaven'tsettledthequestionof__________we'llrenewoursuppliesofcoalforfactory.6)Hedoesn'tknow_________tostayornot.7)Iamnotsure___________I'llhavetimetogowithyou.8)Shedoesn'tknow__________togetmarriednoworwait.9)Idon'tknow_________ornottheywillcomeforourhelp.10)Wediscussed__________weshouldmakeachangeinourplan.11)Heconsidered__________heshouldn'ttellherthesecret.12)Itisunknown_________hewillcome.13)Idon'tknow_________theywillcometohelpus.14)Iamnotcertain___________thetrainwillarriveontime.15)____________thenewsistrueremainsaquestion.16)Whatwewanttoknowis___________hewillcometospeaktoustomorrow.17)Thequestionis___________theycantakeouradvice.18)Letmeknow_____________youcan’tmeetmeatJacksonandThroopStreetsWednesdayafternoonattwoo’clock.19)Wewerediscussing__________weshoulddiscussthebusinesswiththem.20)Thequestion__________we'llbuildanotherlecturehasn'tbeensettled.21)Thequestion____________he'llcomeisunknown.22)Tellme__________itisnotgoingtorain,please.23)Idon’tcare________hedoesn’tshowup.24)Pleaseletmeknow__________youintendtocome.25)Letmeknow___________hehasleftforShanghai.1)if/whether2)whether3)whether4)whether5)whether6)whether7)whether/if8)whether9)whether10)whether11)if12)whether13)whether/if14)if/whether15)Whether16)whether17)whether18)if19)whether20)whether21)whether22)if23)if24)whether25)whether