高二英語虛擬語氣課件

1、虛擬語氣虛擬語氣the subjunctive mood 英語動詞有三種語氣：陳述語氣，英語動詞有三種語氣：陳述語氣，祈使語氣，虛擬語氣。祈使語氣，虛擬語氣。一、一、 陳述語氣陳述語氣 用來陳述一個事實，或提出一個看法。有用來陳述一個事實，或提出一個看法。有肯定，否定，疑問或感嘆等形式。肯定，否定，疑問或感嘆等形式。there are two sides to every question.they didnt watch fireworks yesterday evening.what can i do for you ?例如: shall i turn on the radio? how

2、disappointed tom was ! what lovely flowers those are!二、二、 祈使語氣祈使語氣 用來表示說話人的請求，命令或勸告等。用來表示說話人的請求，命令或勸告等。動詞要用原形，其否定式在動詞前加動詞要用原形，其否定式在動詞前加do not. let me have a try. dont be late again. dont say it in chinese. say it in english. lets go and play basketball.三 虛擬語氣 表示說話人所說的話不是事實，而是表示說話人所說的話不是事實，而是一種與事實相反的

3、假設，愿望，猜測一種與事實相反的假設，愿望，猜測或建議等等?；蚪ㄗh等等。三 虛擬語氣 （一）在條件句中的用法（一）在條件句中的用法 1 與現(xiàn)在事實相反與現(xiàn)在事實相反條件狀語從句謂語條件狀語從句謂語主句謂語主句謂語動詞過去式動詞過去式should/would/ could /might+動詞原形動詞原形例如: if i had time now, we should read it again. if she knew about it, she would come. if he were here, everything would be all right.if i _you , i wo

4、uldnt return the call.a. be b. am c. was d. were 2 與過去事實相反條件狀語從句謂條件狀語從句謂語語主句謂語主句謂語had +過去分詞過去分詞should/would/could/might +have +過去分詞過去分詞例如: if he had seen you yesterday, he would have asked you about it. if i had had the money last year, i would have bought a car. if they had known her address, they

5、would have written to her.ex1. if i _more time, i would have gone with you.a. had b. had had c. have had d. would have ex2. if i had known that, i _ so .a. wouldnt do b. wouldnt have done c. wont do d. have not done bb3 與將來事實相反與將來事實相反條件狀語從句謂語條件狀語從句謂語主句謂語主句謂語動詞過去式動詞過去式should/would/could/might + v原原形形

6、should +v 原形原形were to +v原形原形例如: if it were sunday tomorrow, i would go to see my friends there.if she should come, i should ask her for help.if you were to fail to catch the train, you might take the bus.1. if it_ tomorrow, what would we do?a. rains b. were to rain c. would rain d. rain 2. if it sho

7、uld rain, i _go there tomorrow.a. will b. would not c. wont d. would not have bb補充1.without (沒有),but for(要不是), otherwise(否則), 這些詞可以表示某種假設情況,從而省略條件句.i was busy last week, i to see you.= i was busy last week, if i busy last week, i to see you electricity, human life_ quite different today.a. is b. wil

8、l be c. would have been d. would be if there were no electricity,2. the party, he _of hunger 30 years ago. a. would have died b. would diec. must die d. must have died if there hadnt been the party, he.da3. i was busy yesterday, i _your birthday party.a. attended b. have attended c. would attend d.

9、would have attendedif i hadnt been busy, i d補充2.錯綜時間條件句 主句謂語動詞所表示的動作和條件從句謂語動詞所表示的動作并不是同時發(fā)生,這時動詞的形式并不完全按照上述表格形式進行,而需要按照各自的時間來調(diào)整,這樣的句子就叫錯綜時間條件句.例如1: if you had followed the doctors advice (then), you all right . 如果你那時聽了醫(yī)生的話如果你那時聽了醫(yī)生的話,你你就好了就好了. (主句與從句發(fā)生的時間不同主句與從句發(fā)生的時間不同,應按照主句與應按照主句與從句各自的時間做調(diào)整從句各自的時間做調(diào)

10、整.) if you had followed the doctors advice, you all right . 如果你那時聽了醫(yī)生的話如果你那時聽了醫(yī)生的話,你你就好了就好了. (主句與從句發(fā)生的時間同時主句與從句發(fā)生的時間同時.)例如2: if you had watered them more ,the crops still better. 如果你再給莊稼多澆些水,他們會長得更好.(指現(xiàn)在長得更好.) if you had watered them more, the crops still better. (表示對過去的虛擬) 如果你早就給莊稼多澆些水,他們就會長得更好例如3如

11、果到現(xiàn)在我還沒有寫完作文,我明天就還得寫它. (從句表示與過去事實相反,主句表示與將來事實相反.) if i my composition by now, i on it tomorrow. 如果他昨天把功課都準備好的話,他現(xiàn)在就不會這么困難. if he well for his lessons yesterday, he so many difficulties .1. if you were older (對現(xiàn)在進行虛對現(xiàn)在進行虛擬擬), i _ you to go there yesterday(對過去進行虛擬對過去進行虛擬).a.will allow b. should allow

12、c. would have allowed d. had allowed c補充三:倒裝形式表示虛擬條件句 從句中有were ,had ,should或would等詞語,可以將if省略,同時were ,had ,should或would提至句首,構(gòu)成倒裝.表示虛擬條件 (1) if i her, i her. = i her, i would tell her.(萬一) (2) if i in your position, i it better. = i in your position, i would do it better.(3). if they preparations, the

13、y . = they made preparations, they would have succeeded.1._, i would take an umbrella with me. a. had i been you b. i were you c. were i you d. i had been you c( 二二)在動詞在動詞wish后面的賓語從句中，表示不后面的賓語從句中，表示不可能實現(xiàn)的愿望，其動詞形式有三種可能實現(xiàn)的愿望，其動詞形式有三種 1 表示與現(xiàn)在事實相反的愿望，謂語動詞用表示與現(xiàn)在事實相反的愿望，謂語動詞用過去式。過去式。 i wish i had time to

14、read. i wish i knew her address.2 表示與過去事實相反的愿望，或表示已經(jīng)表示與過去事實相反的愿望，或表示已經(jīng)發(fā)生的一件遺憾事，謂語動詞用發(fā)生的一件遺憾事，謂語動詞用“had +動動詞過去分詞詞過去分詞”。 i wish i had studied very hard. he wishes he hadnt spent so much money.3 表示將來難以實現(xiàn)的或很可能相反的愿望，表示將來難以實現(xiàn)的或很可能相反的愿望，謂語動詞用謂語動詞用“”。 i wish he would be more careful. i wish he would do the

15、job better. she wishes i would go with her.1. i wish i _ able to tell him all about it last night.a. was b. were c. had been d. should be 2. how i wish i _to repair the watch! i only made it worse.a. had tried b. hadnt tried c. have tried d. didnt try 3. i wish i _what to do .a. knew b. have known c

16、. know d. would knowcba4. he wishes _mistakes.a. he doesnt always make b. he didnt always makec. he wouldnt always make d. he wouldnt always making 5. i wish _.a. he were b. he leaves me alone c. he be left d. he would leave me alonecd(三三)虛擬語氣在其他從句中用法虛擬語氣在其他從句中用法 1. 在在“it +be +某些形容詞或過去分詞某些形容詞或過去分詞+t

17、hat”的句型中，主語從句中的動詞形式的句型中，主語從句中的動詞形式常用常用“(should)+動詞原形動詞原形”。 常用的形容詞有：常用的形容詞有：necessary, important, impossible, natural, strange 常用的過去分詞通常是表示建議，常用的過去分詞通常是表示建議， 要求，命令要求，命令等等suggested, required, requested, demanded, ordered, desired, advised,例如:it is natural that he should say so.it is necessary that the

18、 problem should be discussed at once.例如 it is really strange that the girl _ so early. a. has been married b. has married c. be married d. would marryc2.表示建議表示建議.要求要求.命令類的名詞性從句命令類的名詞性從句一堅持一堅持. insist 二命令二命令, order, command三建議三建議,advice, suggest, propose,四要求四要求demand, require, request, desire ，通常用，通常

19、用“should+動詞原動詞原形形”。should可以省略可以省略例如he suggested that we should visit the palace right away.she proposed that the meeting be put off.he ordered that they should start off immediately.i demanded that he should answer me at once.在表示建議，要求，命令等名詞之后的表在表示建議，要求，命令等名詞之后的表語從句，同位語從句中，通常用語從句，同位語從句中，通常用“should+動詞

20、原形動詞原形”。 這些名詞有：這些名詞有：idea, proposal, order suggestion, decision, advice his proposal is that the meeting (should) be put off. our suggestion is that you (should) be the first to go.4.as if ,as though as if ,as though引導的從句可以用來表示引導的從句可以用來表示猜測，假定，謂語動詞在從句中用猜測，假定，謂語動詞在從句中用表示表示，用用“”表示表示。 he is running abo

21、ut as if he were a mad man. they talked as though they had been friends for years.1.the two strangers talked as if they_ friends for years.a.were b. would be c. have been d. had been d但是,需注意: 如果引導的從句所表示的內(nèi)容與事實相符合,應該用陳述語氣: it looks as if our team is going to win (場上情況表明有可能) it seems as if it is going

22、to rain 各種跡象表明天要下雨各種跡象表明天要下雨.一試身手 1.it seems as if it _rain. a. will b. is going to c. is to d. were going to 2.you talk as if you _there. a. were really b. has really been c. had really been d. would really bebc5. 在在“its (about, high) time + that從句從句”結(jié)構(gòu)中，從句中謂語動詞用結(jié)構(gòu)中，從句中謂語動詞用表示一表示一種建議，意思是種建議，意思是“該做某

23、事了該做某事了”。也可以。也可以you look so tired tonight. its time you went to bed.its high time you got up.it is time we started off.1.it is high time that we _ off a. are b. were c. be d. will be b6.if only句型句型“要是要是該多好?。≡摱嗪冒。　敝^語動謂語動詞用法同詞用法同wish,謂語動詞用謂語動詞用表示虛擬語氣。表示虛擬語氣。if only i could see him now. if only i hadnt

24、 lost it.if only i _ how to operate a computer as you do.a. had known b. would knowc. should know d. knew d7. would ratherhad rather后跟從句，后跟從句，謂語動詞通常用過去式表示與現(xiàn)在或者謂語動詞通常用過去式表示與現(xiàn)在或者將來的虛擬，用過去完成式表示對過去將來的虛擬，用過去完成式表示對過去的虛擬。的虛擬。 i would rather you came tomorrow id rather you hadnt accepted their invitation ye

25、sterday. i would rather you had not done it.1. id rather you _ right away.a. leave b. left c. will leave d to leave b8. lest ,in case ,for fear that 唯恐，以免唯恐，以免 從句謂語動詞使用從句謂語動詞使用should +動詞原形動詞原形 be quiet in case you should wake the baby.9.本來應該做的事情而沒有做本來應該做的事情而沒有做 本來不應該做的事情而做了本來不應該做的事情而做了 you should ha

26、ve come here earlier.i ought not to have eaten so much chicken.； 網(wǎng)上配資平臺 http:/ 網(wǎng)上配資平臺 ； 卻被葉媚給婉拒了,用不著別人來服侍他們.玄高說有事,就先行離開了,只留下根漢和葉媚呆在這里.哎,還得在這里等壹個月呀.玄高走后,葉媚便有些感嘆好像要等挺久.其實她心里,反倒是覺得這樣子挺好,不用馬上就離開了,或許就可以和根漢單獨相處了.這種感覺很奇怪.根漢問她：你怎么沒有成親呢?這又隔了好久了哦.又時隔了近二百年了,根漢好奇這女人怎么還沒有成親呢.葉媚面色微紅說：哪有這么容易就找到對脾氣呢,感情這種事情還是要講究緣分,咱

27、可不像你們男人哦,男人可以有許多女人,女人卻終究只是為了等壹個男人.這倒也是.根漢淡淡笑了笑,然后和葉媚壹道走進了這座客殿,雖然只是壹座客殿,但也是足夠奢華了,絕對是皇宮級別寶殿.里面住宿,彈琴聲樂,還有靈池,澡堂子,等壹切東西是應有盡有.根漢二人在這里住下,倒也是壹件愜意事情,在漫長旅途,即將到來九龍淵風云之前,能在這里小住壹個月,也算是壹種難得享受了.既然只有他們兩人了,葉媚便纏根漢給她講講,這些年他在外面經(jīng)歷事情,還有許多道法方面問題想向根漢請教.根漢自然是有問必答,雖然談不上是指導,但是對葉媚來說,能和根漢論論道,聽聽他故事,也是壹件很有意義事情.她聽得很入神,根漢也講得很起勁,或許是

28、難得有這樣聽眾,聽自己故事,根漢投入了不少感情,描述他這些年經(jīng)歷事情.在聽聞十三玄天,竟然大把都是吞噬類修行者,壹個小小圣者,就能吞噬掉上億普通人之后,葉媚也覺得有些不可思議.這世上竟然有那樣地方,與十三玄天相比,這十域之內(nèi),真就是天堂了.還有南沙城,楓千里,天責這些強大準至尊,也令葉媚心生景仰之心,這世上強者確實是太多了,自己還需要努力哦,與這些強者還是有很大差距.而根漢也傾聽了葉媚故事,葉媚這幾百年自然也經(jīng)歷了許多事情.身為葉家家主,她見多了這樣那樣事情,而且十域之內(nèi)大事小事,葉家都會匯報到她這里來,所以她知道事情,比之譚塵絕對不會少.而且她還告訴了根漢壹些譚塵所不知道事情,比如根漢二師兄

29、,歐奕事情,她就知道壹些.原來在八十年前,葉家所管轄壹片領地之內(nèi),出現(xiàn)了壹成片古墓,有人在那里見到了歐奕.只是歐奕狀態(tài)有些奇怪,就像是壹個活死人似,游走于古墓之內(nèi),不知道在那里面做什么,有壹些別強者遇到了歐奕全部被拍死了.而葉家弟子,可能是因為歐奕知道這些人是葉家人,所以便沒有出手擊殺他們.至于什么叫活死人,葉媚形容了壹下,大概就是好像有些靈魂出竅感覺,只是并不是她親眼看到了,所以也不能確定歐奕到底是壹個什么狀態(tài).另外還有壹則最有用消息是,葉媚說她在十五年前,曾經(jīng)見到過根漢小師妹,壹個自稱是惜夕女人.這對根漢來說,可以說是極有用,因為小師妹惜夕已經(jīng)有七八百年沒有見面了,現(xiàn)在不知道怎么樣了,現(xiàn)在

30、自己乾坤世界中,還有兩口神棺,里面有惜夕前兩世之軀.根漢還以為葉媚是看錯了,那不是自己小師妹,不過葉媚卻是給根漢烙出了壹副影相,從影相上來看,確實就是惜夕無疑.只不過與當年柔弱小師妹相比,如今惜夕已然是壹個絕世大美人,仙姿不凡之女人了,比之當年小師妹,氣質(zhì)上不止提升了百倍千倍.不過從她眼神里那種光亮,根漢就能肯定那確是惜夕,有些東西不會隨著你修為提升,就會輕易抹滅掉.（正文貳玖貳捌仙陣）貳玖貳玖惜夕消息.ilou.o貳玖貳玖只不過與當年柔弱小師妹相比,如今惜夕已然是壹個絕世大美人,仙姿不凡之女人了,比之當年小師妹,氣質(zhì)上不止提升了百倍千倍.不過從她眼神里那種光亮,根漢就能肯定那確是惜夕,有些東

31、西不會隨著你修為提升,就會輕易抹滅掉.至少現(xiàn)在可以確定惜夕還活著,至于她到底是什么來頭,又如何想長生不死,根漢也管不著,她活著就好了,這對自己來說就可以了.葉媚曾經(jīng)見過惜夕,但是卻并沒有與她聊過,只是站在遠處聽別人說,那好像是無心峰小弟子,也就是根漢師妹,所以她才特意留意了壹下.據(jù)葉媚回憶,那時遇到惜夕時候,她實力自己完全看不透,不知道是不是已經(jīng)成了準至尊了.對于這樣結(jié)果,根漢壹點也不意外,惜夕天賦絕對是恐怖,比之金娃娃這些師兄,也不差分毫.而且她本身就是血脈特別,當年因為血脈封印解開之后,便出去歷練了,其修為更是壹日千里.再加上她身世如此詭秘,來頭肯定是驚天動地,首先是用萬族之血淬體,然后又

32、有前面兩世,有可能是三生體質(zhì).(而普天之下,又有一些人可以是這種體質(zhì),可以活出三世來,甚至有可能和老瘋子壹樣不死不滅.多少人都想像他們這樣,長生不死,永世不滅呢,但是就連至尊恐怕也沒幾人能真正做到,太古時代至高神們也做不到.可是在這無心峰,現(xiàn)在就有兩個這樣神秘人物,壹個是老瘋子,這個早就不是秘密了,他確實是不死傳奇.還有壹個是惜夕,她竟然有兩世之軀,都存在于世上,至少現(xiàn)在這是她活第三世了,壹個人能夠活出三世來,也是壹個奇跡了.由于傳送陣還得近壹個月才能開啟,根漢和葉媚在這里論論道,也在這里怡怡情,倒也是挺愜意生活.大概過了半個月左右,偏殿外來了兩股很強氣息,根漢老遠就感應到了,這是兩位準至尊來

33、了,這道衍圣地確實是很強大.來是壹個白發(fā)老者,和壹個黑袍中年人,葉媚讓根漢起來相迎,這兩人正是道衍圣地圣主道天,以及他們大長老道淵.晚輩葉媚見過圣主了.見到道天和道淵前來,葉媚自然是以晚輩身份自居.道天微笑道：葉家主客氣了,咱們可是同輩呢.論地位,他們差不多,壹個是圣主,壹個是圣族家主.只不過論修為,還有論年紀,葉媚就應當是晚輩了.這位是.道天早就盯上了根漢,之所以會親自前來,很大壹部分原因,也是想來看看七長老所說這個,強大無比年輕準至尊.這位是咱們?nèi)~家,根漢.葉媚介紹了壹下.根漢.道天楞了楞,然后說：原來是情圣傳人,老瘋子四弟子,果然是少年至尊呀.前輩言過了.根漢謙虛笑了笑：這回前來貴地打擾

34、,還望前輩別介意.根漢你這是哪里話.道天笑道：論起你和咱來,咱們還有壹些淵緣呢,當年南天老祖請咱去喝你和羽化仙體喜酒時候,咱還見過你呢.原來前輩也來了,都怪晚輩眼拙,剛剛壹下子沒看出來.根漢道歉.道天微笑道：你那時候事情多著呢,哪有空盯著咱這糟老頭子呀.哎,只是南天老祖走太急了壹些,不然話,罷了,罷了此事不再提了,咱們不如進去聊吧.幾人點了點頭,便壹道進入了偏殿.因為傳送陣還有半個月左右開啟,道天這回前來,也是特意前來看看到底是哪壹位年輕準至尊.他沒想到,這人竟然就是根漢,不過他也想到了葉南天當初和自己說話.也許這壹世人族希望,就在這個根漢身上,現(xiàn)在看來葉南天死前所說話,當真是要靈驗了.現(xiàn)在有

35、這么好機會,可以和根漢結(jié)識,他當然不會放過這樣機會,自然是要與根漢論論道,順便再結(jié)交壹下,建立壹些關系.根漢身份很特別,最首先被人所知,應該是他是老瘋子四弟子.也是老瘋子最后收一些弟子之壹,同時他也是情圣傳人,然后人們想到,才會是他是葉家人.畢竟他也是葉家血脈,而且還是譚家女婿,娶了譚家羽化仙體,這件事情當時是人盡皆知了.而且根漢與葉家前任家主,葉靜云關系,也被當時很多人知道,根漢這是壹人就娶了好一些絕代天驕.道天,與道淵,是現(xiàn)在道衍圣地兩位準至尊,另外道天還向根漢葉媚他們透了壹個實情,就是其實道衍圣地之內(nèi),還有兩位準至尊.也就是說,這個道衍圣地竟然有四位準至尊,同時有四位準至尊,可以說是極為

36、強勢壹個圣地了.像這樣事情,壹般是不會輕易告訴別人,尤其是另外兩位準至尊顯然不太為人所知,可以做為底牌到時突然就派上用場.在現(xiàn)在時代,準至尊絕對是可以獨霸壹方人物,可以說可以橫著走也是完全可能.就算是現(xiàn)在根漢,若是和準至尊對戰(zhàn),也不敢說就能滅掉對方,任何壹個準至尊,都有自己類似至尊壹般手段,不是壹個對手就能滅殺他們.在沒有至尊年代,準至尊就是金字塔最頂端那壹小部分存在.不過準至尊數(shù)量如今如此多了,也表明,至尊時代就快不遠了.在這眾多準至尊之中,經(jīng)過壹番競爭,最終總會出現(xiàn)至尊,這就是至尊出現(xiàn)契機已經(jīng)快要到了.壹域就有好幾十位準至尊了,圣者早就多如牛毛了,出現(xiàn)至尊條件已然快到了,再接下來就是真正爭

37、尊時機了.不過道天和道淵,都壹致看好根漢,還有當年楓千里,天責都看好根漢,覺得根漢最有希望問鼎至尊.因為論天資,論悟力,和背景,根漢都要異于常人.當然這些話,根漢也就聽聽算了,誰都想當至尊.他就不信這些老家伙就沒有了爭尊之心了,他們已然到了這準至尊境界了,是人都會想再進壹步,都想問鼎那王座之位.只是他們對自己確實是沒有什么惡意,但也不代表以后就沒有惡意,在尊位面前,如果真要發(fā)生沖突話,也是在所難免.現(xiàn)在他們與自己交好,也是為了將來好相見.若是真出現(xiàn)了至尊之機了,他們肯定也要去爭壹爭,到時最好是不要生死相向,根漢也希望如此.只是這個爭,也是有各種形式,有些是直接比道心,比不過也知道自己徒勞,爭不

38、上這尊位.但是也有壹些固執(zhí)家伙,非要和你拼個生死,你死咱活之后,他才會徹底放棄,而根漢并不想和每壹位準至尊最終都是這樣壹個關系.能夠和同階修行者論道,根漢也欣然接受,每壹個修行者都有自己獨特見解,揚長避短,也是極為重要.道衍圣地如此強勢壹個大圣地,放下面子來,交好自己,自己也要承他這個情,何況他還是葉南天老祖老友呢.<b>（正文貳玖貳玖惜夕消息）貳玖叁0反正咱沒想過.ilou.o貳玖叁0能夠和同階修行者論道,根漢也欣然接受,每壹個修行者都有自己獨特見解,揚長避短,也是極為重要.道衍圣地如此強勢壹個大圣地,放下面子來,交好自己,自己也要承他這個情,何況他還是葉南天老祖

39、老友呢.道天和道淵在這里呆了兩天兩夜,與根漢論道他們也收獲頗豐,而葉媚同時與三位準至尊論道,也令她有巨大收獲,這比自己修行十年八年還要管用.有些東西就是要站在高壹層,你可能才會看得更清楚,而晚輩自然是沒有機會了,通過與前輩請教論道,就有機會提前見識這壹切.困擾你多年問題,可能在這論道過程之中,會令你矛塞頓開,葉媚這幾天就有這樣感覺,好像壹下子就頓悟了.正好離傳送陣開啟還有十來天,葉媚便開始閉壹個小關,等快要開啟時候,讓根漢叫上她.而根漢正好獨自壹人在這偏殿中坐下,他也不會孤獨,因為伊蓮娜爾還蘇醒著,現(xiàn)在正好可以陪著他,根漢也有許多問題想向她請教.她可是至高神,比之天神還要強大不知道多少倍,有些

40、東西問她當然比什么都管用,也會少走許多彎路.+不過她也和小紫倩壹樣,有些東西記不起來,比如壹些自己成名道法,她卻記不起來,也算是壹種選擇性記憶怪人.這壹天,根漢正在偏殿壹處涼亭下躺著,他倚在秋千上,手里捧著壹本古書.這是天責臨別前,贈給他壹本道書,根漢已經(jīng)看了幾百遍了,但還是什么也沒看明白,對于這上面所寫所述之事,就像聽天書壹樣.這書應該就是傳說中無字天書了.伊蓮娜爾在他元靈中和他討論：當年在太古時代時候,就曾經(jīng)有壹本無字天書,引得各方強者爭奪,甚至還有幾位至高神卷進其中,為爭奪此書而大打出手,生靈涂炭.但是后來不知道怎么回事,這本無字天書就消失得無影無蹤了,直到咱快化道之前,都沒有再聽說過這本無字天書消息.根漢有些意外：你怎么斷定這就是那本無字天書?他覺得自己這人品也太好了吧,當年至高神都要爭奪無字天書,自己這么輕易就獲得了.呵呵,這個咱還真不清楚.伊蓮娜爾笑道：這些咱記不得了,只是咱能夠感覺到,這東西就是他們在爭