1、If和whether的區(qū)別if和whether都可譯為"是否"，二者引導賓語從句時通常可以互相替換，口語中多用if代替whether.例如：Askif/whetherheplanstocometothemeeting.而以下幾種情況中,只能用whether:1. 強調兩方面的選擇,特別是句中有ornot時如：Letmeknowwhetheryoucancomeornot.2. 賓語從句前置時.如：Whetherthisistrue,Ican'tsay.3. 引導主語、表語、同位語從句時.如：Whetherthefootballgamewillbeplayeddepe

2、ndsontheweather.(主語從句)Thequestioniswhetherhecandoit.(表語從句)Thequestionwhetherweshouldgowiththemmustbedecidedatonce.(同位語從句)4. 在介詞之后作介詞的賓語時.如：Ihaven'tsettledthequestionofwhetherI'llgobackhome.5. 在不定式前與不定式一起組成詞組時.如：Whethertogoorstayisstillaquestion.6. 在discuss,decide等動詞后作賓語時.如：Wediscussedwhether

3、weshouldgotherebyplane.值得注意的是：if還可以引導條件狀語從句,是"假如；如果"之意,而whether可以引導讓步狀語從句,是"不管；無論"之意.如：Ifyouaskhim,hewillhelpyou.Ishallgo,whetheryoucomewithmeorstayathome.一、if或whether引導賓語從句時,作“是否”講，常放在動詞ask、see、say、know和findout等后面一般情況下，兩者常可換用,在口語中多用if.如:例1Nobodyknowswhether(if)itwillraintomorrow

4、.沒有人知道明天是否下雨.例2Lucyaskedwhether(if)theyhadacottonsweater.露西問他們是否有棉制的羊毛衣.二、if或whether引導賓語從句時，要注意三個方面,即連詞、語序和時態(tài).1 if或whether不能和that或其它連詞(副詞)同時使用，也不能省去如：例3我不知道他今天是否會來.誤Idon'tknowthatif(whether)hewillcomeheretoday.正Idon'tknowif(whether)hewillcomeheretoday.例4他走過來看看貓是否出了毛病.誤Hecametoseewhatif(wheth

5、er)therewaswrongwithhiscat.正Hecametoseeif(whether)therewaswrongwithhiscat.2 if或whether引導的賓語從句時，雖具有疑問意義,但從句語序應用陳述句語序如：例5Didyouknowthewaytothehospital?Theoldwomanaskedme.Theoldwomanaskedme.if(whether)Iknewthewaytothehospital.老婦人問我是否知道去醫(yī)院的路.3if或whether引導的賓語從句應和主句的時態(tài)保持一致.即主句為一般現(xiàn)在時,從句用任一種時態(tài)；主句為一般過去時,從句則用

6、過去時中的任一種時態(tài).如：例6Idon'tknowif(whether)hehascomehere.我不知道他是否來過這兒.例7Tomaskedif(whether)Ihadreadthebook.湯姆問我是否看過這本書.三、if和whether的區(qū)別：1 在動詞不定式之前只能用whether.如：例8Ican'tdecidewhethertostay.我不能決定是否留下.2 在whetherornot的固定搭配中.如：例9Iwanttoknowwhetherit'sgoodnewsornot.我想知道是否是好消息.3在介詞后,只能用whether.如：例10Hisfa

7、therisworriedaboutwhetherhelosehiswork.他的父親擔心是否會失去工作.4賓語從句放在句首表示強調時,只能用whether.如：例11Whethertheycanfinishtheworkontimeisstillaproblem.他們是否能準時完成這項工作還是個問題.5用if會引起歧義時，只用whether.如：例12Couldyoutellmeifyouknowtheanswer?這句話有兩種意思：“你能告訴我是否知道答案嗎?”或“如果你知道答案,請告訴我,好嗎?”.如用whether可避免歧義.if和whether專題1) Idon'tcarey

8、ourcarbreaksdownornot.2) Thisdependsuponwearedeterminedtodoit.3) Itdependsonheisready.4) Iamnotinterestedinyou'llcomeornot.5) Wehaven'tsettledthequestionofwe'llrenewoursuppliesofcoalforfactory.6) Hedoesn'tknowtostayornot.7) IamnotsureI'llhavetimetogowithyou.8) Shedoesn'tknowt

9、ogetmarriednoworwait.9) Idon'tknowornottheywillcomeforourhelp.10) Wediscussedweshouldmakeachangeinourplan.11) Heconsideredheshouldn'ttellherthesecret.Itisunknownhewillcome.Idon'tknowtheywillcometohelpus.Iamnotcertainthetrainwillarriveontime.thenewsistrueremainsaquestion.Whatwewanttoknowi

10、shewillcometospeaktoustomorrow.Thequestionistheycantakeouradvice.Letmeknowyoucan'tmeetmeatJacksonandThroopStreetsWednesdayafternoonattwoo'clock.Wewerediscussingweshoulddiscussthebusinesswiththem.Thequestionwe'llbuildanotherlecturehasn'tbeensettled.Thequestionhe'llcomeisunknown.Tellmeitisnotgoingtorain,please.Idon'tcarehedoesn'tshowup.Pleaseletmeknowyouintendtocome.12)13)14)15)16)17)18)19)20)21)22)23)24)25)LetmeknowhehasleftforShanghai.1) if/whether2) whether3) whether4) whether5) whether6) whether7) whethe