人教版英語八年級上冊第十單元課件_第1頁
人教版英語八年級上冊第十單元課件_第2頁
人教版英語八年級上冊第十單元課件_第3頁
人教版英語八年級上冊第十單元課件_第4頁
人教版英語八年級上冊第十單元課件_第5頁
已閱讀5頁,還剩91頁未讀, 繼續(xù)免費閱讀

下載本文檔

版權(quán)說明:本文檔由用戶提供并上傳,收益歸屬內(nèi)容提供方,若內(nèi)容存在侵權(quán),請進行舉報或認領(lǐng)

文檔簡介

Unit10

Ifyougototheparty,

you’llhaveagreattime!

教學目標:語言知識目標:1)能掌握以下單詞:meeting,video,organize,potatochips,chocolate,upset,taxi,advice能掌握以下句型:①─IthinkI’llgotothepartywithKarenandAnna.─Ifyougototheparty,you’llhaveagreattime!②─Whatwillhappeniftheyhavethepartytoday?─Halftheclasswon’tcome.2)能了解以下語法:掌握含if條件狀語從句的主從復合句的用法。3)能用if引導的條件狀語從句作出假設(shè),用will談?wù)摻Y(jié)果。單詞videoorganizechocolateupsetadvicetravelagentexpertteenagernormaln.錄像,錄像帶

v.組織,籌備n.巧克力;

v.難過,失望n.勸告,建議v.旅行n.代理人,經(jīng)紀人

n.專家,能手

n.青少年adj.正常的單詞unlesscertainlywalletworriedangrycarelessunderstandingtrustmistakecareful除非,如果不adv.當然,肯定n.皮夾,錢包

adj.擔心的,煩惱的adj.生氣的,發(fā)怒的adj.粗心的,不小心的adj.善解人意的,體諒人的

n.相信,信任

n.錯誤,失誤adj.小心的,細致的單詞advisesolveexperiencehalfwayelsev勸告,建議v.解決;解答n.經(jīng)歷;經(jīng)驗

adj.中途的adv.半路地別的,其他的SectionA1a-2dShewillbelate.Ifshe_____toschool,she________late.Sheisgoingtowalktoschool.walkswillbeLead-inItisgoingtoraintomorrow.

Iwillstayathome.

Ifit_____tomorrow,I__________athome.

rainswillstayIfit____

sunnytomorrow,they___________atrip.Itwillbesunnytomorrow.Theywillhaveatriptomorrow.iswillhaveHewon’tstudyhard.Hewillfailintheexam.“Ifhe_______studyhard.He_________intheexam.”doesn’twillfailMatchthestatementswiththepictures[a-d].1a1.___IthinkI’llwearjeanstotheparty.2.

___IthinkI’llstayathome.3.___IthinkI’lltakethebustotheparty.4.___IthinkI’llgotothepartywithKarenandAnna.acbdListeningListenandcompletetheresponsesin1a.1bIfyoudo,theteacherswon’t________Ifyoudo,you’ll________________Ifyoudo,you’ll____________________Ifyoudo,you’ll____________________haveagreattime.belate.letyouin.besorry.讓你進來感到抱歉遲到玩得開心Areyougoingtothepartytomorrownight?Yes,Iam.Pairwork1cLookatthepicturesandmakeconversations.Whowillyougowith?Ifyoudo,you’llhaveagreattime.IthinkI’llgowithKarenandAnna.NewWordsvideon.

錄像帶;錄像potatochips炸土豆片;炸薯條Isthevideoonthebookshelf?錄像帶在書架上嗎?I’dlikesomepotatochips,please.我想買些薯條。

frenchfrieschocolaten.

巧克力Ilikechocolateice-creambest.我最喜歡巧克力冰淇淋。meetingn.會議;集會;會面

IsthemeetingonWednesday?會議是在星期三嗎?

meetingroom會議室

organizev.

組織;籌備Let’s

organize

asoccergame.讓我們組織一次足球比賽吧。organiz+a+tion=organization

n.

組織;機構(gòu);團體e.g.Iworkforavoluntaryorganization.ListeningListenandcirclethecorrectanswerstocompletethesentences.2a1.Thestudentsaretalkingaboutwhentohave

(aclassparty/aclassmeeting/abirthdayparty).2.Theyplantohaveiton(Fridayevening/Saturdayafternoon/Saturdayevening).halftheclasswon’tcome;somestudentswillbebored;makesomefood;studentswillleaveearly;thepartygames1.Whatwillhappeniftheyhavethepartytoday?______________________________Halftheclasswon’tcome.Listenagain.Choosethecorrectshortanswerintheboxtoanswereachquestion.2b2.Whatwillhappeniftheyhavethepartytomorrow?_________________________________3.Whatwillhappeniftheywatchavideoattheparty?__________________________________

Studentswillleaveearlytostudy.Somestudentswillbebored.4.WhatwillMarkorganize?_________________________________5.WhatwillNellydo?_________________________________Thepartygames.Shewillmakesomefood.PairworkRole-playaconversationbetweenNellyandMark.OK,whenisagoodtimetohavetheparty?Let’shaveittoday.2cHmm.Ifwehaveittoday,halftheclasswon’tcome.Whynothaveitontheweekend?Ok,goodidea.2dReadingReadtheconversationandanswerthequestions.1.Whatwillhappen

ifweaskpeopletobringfood?__________________________________________________________________________2.Whatwillhappen

ifwegivepeoplesomesmallgiftsiftheywin?___________________________________Morepeoplewillwanttoplaythegames.They’lljustbringpotatochipsandchocolatebecausethey’llbetoolazytocook.他們將只帶薯條和巧克力,因為他們太懶以至于不想煮飯將有更多的人想要玩這個游戲。Hey,Ben.Forthepartynextweek,shouldweaskpeopletobringfood?No,let’sorderfoodfromarestaurant…Role-playtheconversation.…Role-play1.askv.要求,請求;詢問用法:①

asksb.todosth.請求/要求某人做某事e.g.Heaskedthedoctor

to

tellhimthetruth.②

asksb.aboutsth.就某事詢問某人e.g.MayIaskyousomethingaboutyourfriendTom.③ask(sb.)forsth.向(某人)尋求...e.g.Pleaseasktheteacherforhelp.Languagepoints2.Yes,thegameswillbemoreexciting,too.

exciting意為“令人興奮的;令人激動的”e.g.Themoviehasanexcitingopening.excitedadj.興奮的(修飾人)e.g.IfeelexcitedwhenIhearfromyou.Exercises用括號內(nèi)所給單詞的正確形式填空。1.I’llbuyacomputerifI_______(have)enoughmoney.2.I’msureifhe_____(go)totheparty,he________(have)agreattime.havegoeswillhave3.You___________(notget)nervousifyou_____(do)enoughexercise.4.Ifshe_______(finish)workearly,she______(go)home.5.Ifit_____(rain),we________(stay)athome.dofinisheswillgorainswillstaywon’tgetSectionAGrammarfocus-3c1.我想我將會乘公共汽車去參加聚會。I_____I’lltakethebustothe______.2.如果你那樣做,你將會遲到。Ifyou_____,_____belate.Grammarfocusdoyou’llthinkparty根據(jù)課本內(nèi)容,完成下列句子。3.我想我將待在家里。I__________stayathome.4.如果你那樣做,你將會覺得很抱歉。Ifyou____,__________sorry.5.如果他們今天聚會,將會發(fā)生什么事?_______________ifthey_____thepartytoday?thinkI’lldoyou’llbeWhatwillhappenhave6.如果他們今天聚會,班里一半的學生將不會去。Ifthey______thepartytoday,______theclass_______come.7.我們應(yīng)當要求人們帶食物來嗎?

Shouldwe______peopleto______food?havehalfwon’taskbring8.如果我們要求人們帶食物來時,他們將會只帶薯條和巧克力。______we______peopletobringfood,________just______potatochipsandchocolate.Ifaskthey’llbring例如:Wewillgototheparkifit_____________(rain)tomorrow.Grammar

含if條件狀語從句的主從復合句1.if條件狀語從句中,主句用一般將來時,從句用___________表示將來。

________原則。doesn’t主將從現(xiàn)rain一般現(xiàn)在時2.if條件狀語從句中,如果主句有must,can,may

等情態(tài)動詞,從句用___________。

例如:Youmuststopifthetrafficlight____(be)red.is一般現(xiàn)在時3.if條件狀語從句中,主句是祈使句,從句用____________表示將來。

_________原則。一般現(xiàn)在時主將從現(xiàn)例如:Don’twaitformeifI_____(be)late.amFinishthefollowingsentencesaccordingtotheexample.

ifwillshe,callme,

I,tellheraboutitIfshecallsme,Iwilltellheraboutit.

he,come,nextweekend,

I,tellyou

Ifhecomesnextweekend,Iwilltellyou.

notrain,

gohiking,thisafternoon

Ifitdoesn’train,Iwillgohikingthisafternoon.

nowar,

theworld,morebeautifulIfthereisnowar,theworldwillbemorebeautiful.

he,havefreetime,

gotoShanghai

Ifhehasfreetime,hewillgotoShanghai.upsetadj.

難過;失望;沮喪e.g.MomwillbeupsetifIforgetitagain.如果我再忘記,我媽媽會失望的。Newwordse.g.You’dbetterorderataxi.你最好提前預(yù)定一輛的士。taxin.

出租車;的士advicen.

勸告;建議(不可數(shù)名詞)

e.g.Canyougivemesomeadvice?能請你給我一些建議嗎?短語e.g.Letmegiveyouapieceofadvice.我來給你出個點子。apieceofadvice/awordofadvice一條建議;一則忠告DearSuMei,Idon’t______(know)what______(do)about_______(go)toMike’sbirthdaypartytomorrownight.Myparents_____(think)Ishouldstudy______myEnglishexamnextweek.IfI_____(go)totheparty,they_______(be)upset.3aFillintheblankswiththecorrectformsoftheverbsinbrackets.knowtodothinkforwillbegoinggoMike______(tell)ustowearniceclothes,butIdon’t________(have)any.IfI_______(wear)jeans,I_______(look)theworst.Also,I’mnotsurehow______(go)totheparty.IfI______(walk),it________(take)metoolong.IfI_______(take)ataxi,it______(be)tooexpensive.Canyougivemesome__________(advice)please?TinatellshavewearwilllooktogowalkwilltaketakewillbeadviceCompletethesentencesusingyourownideas.1.IfIgetuplatetomorrow,___________2.IfIdon’tfinishmyhomework,______3.IfIdon’tgetenoughexercise,_______4.Iwillnothaveenoughtimetostudyif____________________5.Iwillnotmakeanyfriendsif__________3b1.I’llbelateforschool.2.Myparentswillbeupset.3.I’llbecomeveryheavy.4.Iplaychessafterschooleveryday.Possibleanswers5.Idon’tgotomyfriends’parties.SectionB1a-2ee.g.Childrenunderfiveusuallytravelfreeontrain.五歲以下的孩子乘火車通常是免費的。agentn.

代理人;經(jīng)紀人

e.g.Mr.LinisanagentforAPPLE.林先生是蘋果公司的代理人。Newwordstravelv.&n.

旅行;游歷Lead-inSomeimportantthingsinourlife.behappygotocollegemakealotofmoneybefamoustravelaroundtheworldgetaneducationWhichofthethingsbelowarethemostimportanttoyou?Circlethreethings.behappytravelaroundtheworld1agotocollegemakealotofmoneybefamousgetaneducationPairworkWhatdoyouthinkIshoulddo?Canyougivemesomeadvice?Ithinkyoushouldgotocollege.ButifIgotocollege,I’llneverbecomeagreatsoccerplayer.StudentAisMichael.StudentBishisfriend.StudentB,giveStudentAadvice.DiscussWhatkindsofthingsdoyouworryabout?Whodoyouusuallygotoforhelp?2aI’mnotgoodatmath.Iusuallyworryaboutit.Iusuallygotomymathteacherforhelp.walletn.

錢包teenagern.(13~19)

青少年milen.

英里Newwordse.g.It’samile’swayfrommyhometoschool.從我家到學校有一英里。expertn.

專家normaladj.

正常的;一般的e.g.Itwasanormalsummernight.那是一個尋常的夏夜。反:abnormaladj.不正常的unlessconj.

(=ifnot)除非;如果不e.g.You’llbelateunlessyougoatonce.=You'llbelateifyoudon'tgoatonce.understandingadj.善解人意的;體諒人的e.g.Mr.Liisaveryunderstandingperson.李先生是一位很善解人意的人。himselfpron.

他自己themselvespron.

他(她/它)們自己反身代詞:賓格或物主代詞+self/selvese.g.TheoldmantaughthimselfEnglish.那位老人正在自學英語。反身代詞的固定搭配:

byoneself(靠)自己

enjoyoneself過得愉快

helponeselfto隨便吃

talktooneself自言自語

dressoneself穿衣服

keep…tooneself保守秘密

e.g.It’scertainlyagoodsuggestion.這無疑是一個好建議。certainlyadv.

當然;行;無疑;肯定e.g.Shemademistakesagainandagain.她三番五次地犯錯。makeamistake/makemistakes犯錯誤mistaken.

失誤;錯誤e.g.Mr.MillerwasveryangrywithTom.米勒老師對湯姆很生氣。angryadj.

生氣的;發(fā)怒的①beangrywithsb.對某人生氣②beangryat/aboutsth.對某事生氣careful

adj.

細致的;精心的;慎重的e.g.Heisacarefuldriver.He’snevercarelessindriving.

反:careless

adj.

粗心的;不小心的carefully

adv.

粗心地;不小心地關(guān)于care的詞組:

takecareof照顧carefor喜歡;照顧careabout關(guān)心;在意advisev.

勸告;建議e.g.Thedoctoradvisedmetogiveupsmoking.醫(yī)生建議我戒煙。advise(動詞)→advice(名詞)建議(不可數(shù))advisesb.todosth.建議某人做某事近:suggest(suggestion)建議用法:suggestdoingsth.suggestion為可數(shù)名詞experiencen.

經(jīng)驗;經(jīng)歷e.g.Hehasnoexperienceatall.halfwayadv.

在中途;部分地做(或達到)e.g.Shelostherwayhalfwaytothezoo.她在去動物園的路上迷路了。inhalf分成兩半e.g.Shecutthecakeinhalf.她將蛋糕切成兩半。注:經(jīng)歷可數(shù),經(jīng)驗不可數(shù)Fillintheblankswiththephrasesinthebox.

2ddiscussyourproblemstellherparentsunlessyoutalkrunawayfromtalktosomeoneshareherproblemstodonothingStudentsoftenhavealotofproblemsandworries.LauraMillsthinkstheworstthingis_____________.Shethinksyou’llfeelworseifyoudon’t______________aboutyourproblems.Lauraremembersthatsheoncelostherwalletandwasafraidto_____________aboutit.Nowshebelievesyoucannotfeelbetter_______________tosomeone.todonothingtalktoanyonetellherparentsunlessyoutalkShesaysshewillalways__________________inthefuture.RobertHuntagreeswithLaura.Hethinksyoushouldnot_______________yourproblems,butyoushouldtrytosolvethem.IfyoucannottalktoanexpertlikeRobert,youcan____________________withyourparentsbecausetheyhavealotofexperience.shareherproblemsrunawayfromdiscussyourproblems1.Ifpeoplehaveproblem,theyshould

keepthemtothemselves.keep意為“保留;保存”,keepthemtothemselves意為“把問題(煩惱)埋在心底,不向他人傾訴”。例如:Youcankeepthetoyifyoulike.要是你喜歡那個玩具的話,可以把它留下。Languagepoints2.Shejustkeptthinking,“IfItellmyparents,…”

此句中,keep表示“(使……)保持(某種狀態(tài)或關(guān)系);一直……”,后面接動詞時,該動詞要用-ing形式,形成keepdoing…結(jié)構(gòu)。例如:Itkeptrainingforaweek.雨一直下了一周。3.Lauraoncelostherwallet,andworriedfordays.

once用作副詞時,意為“曾經(jīng);一

度;從前”。它是一個不確定的時間副詞,其位置一般是在行為動詞之前,系動詞之后。如:

OncehelivedinAmerica,butnowhelivesinEngland.他曾經(jīng)生活在美國,但現(xiàn)在他生活在英國。4.Theygotheranewwalletandaskedhertobemorecareful.

get意為“買”,相當于buy,但不如后者正式。如:Couldyougetmeaticket,please?請給我買張票好嗎?5.Itisbestnottorunawayfromourproblems.Weshouldalwaystrytosolvethem.trytodosth.努力做某事

如:Pleasetrytofinishthisworkinthirtyminutes.

請盡量在30分鐘完成這項工作。trydoingsth.試著做某事tryone'sbesttodosth.盡力做某事例:

—Iusuallygotherebytrain.

—Whynot_________byboatforachange?

A.totrygoingB.tryingtogo

C.totryandgoD.trygoing6.InEnglish,wesaythatsharingaproblemislikecuttingitinhalf.1)sharing動名詞作主語;2)cut…inhalf表示“把……切成兩半;把……一切為二”,inhalf/halves是一種固定結(jié)構(gòu),介詞in表示狀態(tài)。如:Pleasecuttheappleinhalf.7.Soyou’rehalfwaytosolvingaproblemjustby

talkingtosomeoneaboutit!1)behalfwayto…表示“完成了或做了事情的一部分”,這里的to是介詞。如:We’restillonlyhalfwaytofinishingthehomework.我們才僅僅完成了一部分作業(yè)。2)by在此表示方式,意為“通過(……辦法,方式)”如:WecanlearnEnglishbysingingEnglishsongs.我們可以通過唱英文歌來學英語。根據(jù)漢語意思完成句子1.一些人認為最糟的事情是什么也不做。Somepeoplebelievethe________thingis________________nothing.2.我認為和某個人談?wù)勈呛苡袔椭?。Ithink________tosomeone________alot.3.如果我們不和某個人談?wù)劊覀円欢〞X得更糟。________wetalktosomeone,we'll________________________.4.她不敢把那件事告訴她父母。Shewas________________tellherparents________it.5.因此,你只要跟人聊聊這個問題,你就已經(jīng)解決了問題的一半!Soyou're________________________aproblemjustbytalkingtosomeoneaboutit!6.分擔一個煩惱就像把麻煩分成兩半。Sharingaproblemislike________it________________.7.當心!不要摔倒了!________________!Don'tfalldown.8.我們必須對此事保密。Wemust________thisthing________________.Ⅲ.1.worst;todo

2.talking;helps3.Unless;certainlyfeelworse4.a(chǎn)fraidto;about

5.halfwaytosolving6.cutting;inhalf

7.Becareful/Lookout8.keep;toourselves根據(jù)短文內(nèi)容和括號內(nèi)所給漢語意思,寫出空白處各單詞的正確形式(每空一詞)。Asa1.________(青少年),youshouldalwaystakegoodcareofyourself.Ifyouaregoingto2.________(旅行)withoutyourfamily,keepthe3.________(建議)inmind.Andyou'llhaveagoodtime.First,choosearightplace.Youcanaskothersforinformation.Ifeveryonesaysoneplaceis4.________(危險的),youcan'tgotherecertainly.Second,askafriend.Thejourneywillbeeasierandmoreinterestingifyougowithafriendwhohasmuch5.________(經(jīng)驗).Forexample,ifyouare6.________(粗心的),youwillforgetthingseasily.Ifyourfriendgoeswithyou,heorshecanhelpyoualot.Third,makeaplanforthetime,placesandactivities.It'slike7.________(組織)ameeting.Tomakesureeverythinggoeswell,youshouldmakealotof8.________(準備).Fourth,makealistofthethingsyouneedtotake,suchastheIDcard,the9.________(錢包)andthephone.Ofcourse,clothesandanumbrellaarealsoneeded.Ifyouneedanything10.________(其他),youshouldthinkofthesizeofyourbag.It'snotagoodideatotaketoomanythingswithyou.1.teenager

2.travel

3.advice4.dangerous

5.experience

6.careless7.organizing

8.preparations9.wallet

10.elseSectionB3a-SelfcheckMyfriend_______hasaproblem.He/She_____________________________.Ithinkhe/sheshould___________________.Ifhe/she____________________,he/shewill__________________________.Writeaboutyourfriend’sfirstproblemandthepossiblesolutions.Usethestructuresbelowtohelpyouplanyourwriting.Writing3b分析3b中的作文提綱,可以看出。我們需寫三個方面的內(nèi)容就能輕松完成一篇小作文。首先,寫清楚朋友的名字及其現(xiàn)在存在的問題或困難。然后,寫出自己給他的建議。并用if從句來進一步說明自己的建議將會起到的作用。最后,復讀一遍作文來檢查有沒有錯誤。指導MyfriendJennyhasaproblem.Sheistooheavy.Ithinksheshouldeatlessjunkfoodandeatmorevegetablesandfruit.Ithinkshealsoshouldgetmoreexercise.Ifsheeatsmorevegetablesandfruit,

shewilleatlessjunkfood.Ifshegetsmoreexercise,she’llbemuchthinnersoon.PossibleversionNowwriteyouradviceforyourfriend’ssecondandthirdproblem.Usethestructuresin3btohelpyou.Myfriendalsohastwootherproblems.________________________________________________________________________________________________________3c…Sheisalwayslateforschool.Ithinksheshouldn’tstayuplateonweekdays.Sheshouldgetanalarmclock.Sheshouldridesherbiketoschool.Ifshehasanalarmclock,shewillgetupearly.Possibleversion:Ifsheridesherbiketoschool,itwillcostherlesstimetogettoschool.Shethinksphysicsistoodifficultforher.Ithinksheshouldtakenotesinclass.Sheshouldalsodomoreexercises.Sheshouldasktheteacherforhelpafterclass.4Yourschoolistakingpartintheproject“WeCanHelp!”Addmoreitemstotheposter.Thentalkaboutwhatyouwilltakepartintheproject.oldpeople’shomevisitschoolclean-upchildren’shospitalvisit_____________________________Whatwillyoudoifyouvisitanoldpeople’shome?IfIdothat,I’llbringtheoldpeoplesomeflowers.IfIdothat,I’llsinganddanceforthemtomakethemhappy.重點短語待在家里乘公共汽車明天晚上進行班級聚會一半的同學訂購食物炸土豆片,炸薯條最后犯錯誤給某人提一些建議上大學環(huán)游世界stayathome

takethebustomorrownighthaveaclasspartyhalftheclassorderfood

potatochips

intheendmakemistakesgivesb.someadvicegotocollegetravelaroundtheworld重點短語努力工作保守秘密與某人交談因某事生氣在生活中生某人的氣第一步解決問題害怕做某事最好(不)做某事分成兩半得到教育workhard

keep…tooneselftalkwithsb.beangryat/aboutsth.inlifebeangrywithsb.

thefirststep

solveaproblembeafraidtodosth.It’sbest(not)todosth.inhalf

getaneducationA)用方框中所給詞的適當形式填空,每詞限用一次,每空限填一詞46.Be________!Thereisasnakeoverthere.47.Shemadealotof________inherEnglishhomework.48.Hemadeabeautifulbirthdaycardfor________yesterday.49.Who__________isgoingtohaveaholidaywithyou?50.Couldyoupleasegivemesome________onhowtolearnmathwell?mistake,advice,care,else,himcarefulmistakeshimselfelseadvice閱讀短文,用所給詞匯的適當形式填空或根據(jù)上下文填寫出合適的詞匯,使短文通順Thegreatestproblemforteenagersisthattheyaretoostressed(壓力).Gina,a15-year-oldgirl,was________61(worry)aboutherexamsveryoften.Althoughshe________

溫馨提示

  • 1. 本站所有資源如無特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請下載最新的WinRAR軟件解壓。
  • 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
  • 3. 本站RAR壓縮包中若帶圖紙,網(wǎng)頁內(nèi)容里面會有圖紙預(yù)覽,若沒有圖紙預(yù)覽就沒有圖紙。
  • 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
  • 5. 人人文庫網(wǎng)僅提供信息存儲空間,僅對用戶上傳內(nèi)容的表現(xiàn)方式做保護處理,對用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯,并不能對任何下載內(nèi)容負責。
  • 6. 下載文件中如有侵權(quán)或不適當內(nèi)容,請與我們聯(lián)系,我們立即糾正。
  • 7. 本站不保證下載資源的準確性、安全性和完整性, 同時也不承擔用戶因使用這些下載資源對自己和他人造成任何形式的傷害或損失。

評論

0/150

提交評論