If引导的条件状语从句.docx

If引导的条件状语从句1.if引导的条件状语从句可以放在主句之前，也可以放在主句之后，如果放在主句之前，中间要用逗号将主句和从句隔开。例如：IfIamfree,Iwillcometoseeyou.=IwillcometoseeyouifIamfree.如果我有空，我就来看你。2.在含if引导的条件状语从句的复合句中，主句用一般将来时，从句通常用一般现在时态表示将来意义，即“主将从现”原则。例如：Ifitsnowstomorrow,wewillgoskiing.如果明天下雪，我们就去滑雪。3.在含if引导的条件状语从句的复合句中，语句的谓语还可含有情态动词can、must、may等，主句也可是祈使句。例如：Ifitstopsraining,wecangoout.如果雨停了，我们就能出去。4.在含if引导的条件状语从句的复合句中，如果主句部分描述的是客观事实或真理，要用一般现在时。例如：Ifyouheattheice,itturnsintowater.如果你加热冰，它就会变成水。if引导的非真实条件句对过去的虚拟条件从句(if):主语+haddone主句might/would/should/could+havedone对现在的虚拟if+主语+动词过去式(be用were)主句might/would/should/could+do对将来的虚拟if+主语+动词过去式(be用were)或主语+shoulddo或主语+weretodo主句might/would/should/could+doe.g.Tomgottothestationintimebecausehestartedearlier.IfTomhadstartedlate,hewouldhavemissedthetrain.Doyouthinkthethiefenteredthroughthedoor?No,ifhehad,Idon'tbelieve,hewouldhavebrokenthelivingroomwindow.Ifthebookweren'tsoexpensive,Iwouldbuyit.Ifyoudidn'tlivesofaraway,wewouldbeabletovisityoumore.Whatwouldyoudoifyoulostyourpassportinaforeigncountry?Whyhasn'thecome?Ifheshouldnotcomeontime,wewouldhavetoputoffthetrip.2.注意事项e.g.Ifshehadn'tworkhardatEnglishinthepast,shewouldn'tworkaswellasasecretaryinalargecompanynow.混合时间的虚拟语气从句为对过去的虚拟，主句是现在。Hadwenotusedanout-of-datetimetable,wewouldn'thavemissedthetrain.if引导从句的倒装从句相当于ifwehadnotusedanout-of-datetimetable,同样，were还有should在从句中都可以提前，省略if.Ifonly要是...就好了IfonlyIwereyounger!IfonlyIhadworkedharderinmyteenageyears!IfonlyIshouldtraveltomorrow!虚拟语气的十大句型一、虚拟条件句：条件状语从句是非真实情况，在这种情况下要用虚拟语气。1.条件从句与现在事实不一致，其句型为：句型1：If+主语+过去时，主语+should(could,would,或might)+动词原形(1)IfIwereyou,Iwouldstudyhard.(2)Ifitrained,Iwouldnotbeherenow.2.条件从句与过去事实不一致，其句型为：句型2：If+主语+had+过去分词，主语+should(could,would,或might)+have+过去分词(3)Ifthedoctorhadcomelastnight,theboywouldhavebeensaved.(4)IfIhadnotstudiedhard,Iwouldhavefailedintheexamlastterm.3.条件从句与将来事实不一致，其句型为：句型3：If+主语+过去时/should+动词原形/wereto+动词原形，主语+should(could,would,或might)+动词原形(5)Ifitshouldraintomorrow,wewouldstayathome.(6)IfIweretogotothemoononeday,Icouldseeitwithmyowneyes.(7)Ifyoumis