英語語法狀語從句的歸納總結(jié)

英語語法狀語從句的歸納總結(jié) 在復(fù)合句中修飾主句或主句中的某一成分的從句叫狀語從句。狀語從句通常由從屬連詞或起連詞作用的詞組引導(dǎo)，有時甚至不需要連詞直接和主句連接起來。狀語從句根據(jù)它表達(dá)的意思不同，可分為時間、地點、原因、目的、結(jié)果、條件、方式、比較、讓步等九類。 一、 時間狀語從句 時間狀語從句是表示時間關(guān)系的從句?？梢砸龑?dǎo)時間狀語從句的連詞很多，根據(jù)意義和主從句之間的時間關(guān)系，通?？煞譃橐韵聨追N情況：A when, while, as, whenever when, while, as表示主句謂語作和從句的謂語動作同時發(fā)生或幾乎同時發(fā)生。 1when when表示點時間時，從句中用短暫性動詞；表示段時間時，用持續(xù)性動詞。 When I got home, my family were already having dinner. 我到家的時候，全家已在吃晚飯。 （when表示點時間） When they were still talking and laughing, the teacher came in. 當(dāng)他們還在說笑的時候，老師進(jìn)來了。（when表示段時間） He waved ahello when he saw her. 當(dāng)他看見她的時候，就揮手打了個招呼。（when表示點時間） When you think you know nothing, you begin to know something. 當(dāng)你認(rèn)為自己一無所知的時候，就開始知道一些事情了。（when表示段時間） 注意： 當(dāng)when意思是正當(dāng)時候（and at that moment）時，when只能跟在前一分句之后。 He was about to go to bed when the doorbel rang. 他正要上床，忽然門鈴響了。 They were watching the World Cup when suddenly the lights went out. 他們正看著世界杯比賽，突然燈滅了。 They had just arrived home when it began to rain. 他們剛到家，天就開始下雨了。 有時when表示雖然，盡管的含義，相當(dāng)于although或since。 He walks when he might take a taxi. 盡管可以打的，但他還是步行。 How can you hope for mercy yourself when you show none 既然你不寬恕別人，你自己又怎能希望得到別人的寬恕呢？ 2while while通常表示一段時間，從句中宜用持續(xù)性動詞作謂語。 Strike while the iron is hot. 趁熱打鐵。 She fell asleep while she was reading the newspaper. 她在看報的時候睡著了。 while有時可以作并列連詞，表示對比，可譯成而。 I am fond of English while he likes maths. 我喜歡英語而他卻喜歡數(shù)學(xué)。 We slept while the captain kept watch. 我們睡覺而上尉擔(dān)任警戒。 while有時可引導(dǎo)讓步狀語從句，意思是雖然。 While they love te children, they are strict with them. 雖然他們都愛他們的孩子，但卻對他們要求嚴(yán)格。 提示： 雖然during 與 while 意思很相近，但是during是介詞，不能引導(dǎo)從句。 3as as表示點時間時，從句中用短暫性動詞；表示段時間時，用持續(xù)性動詞。as和when兩者經(jīng)?？梢酝ㄓ谩?The thief was caught as when he was stealing in the supermarket. 小偷在超市行竊時被逮住了。 I saw Jim as when he left the meeting room. 吉姆離開會議室時候我看到了他。 as表示 一邊一邊，強調(diào)從句和主句中兩個動作交替進(jìn)行或同步進(jìn)行。 They talked as they walked. 他們邊走邊聊。 He looked behind from time to time as he went. 他一邊走，一邊不時地往后看。 as表示隨著 As time goes on, its getting warmer and warmer. 隨著時間的推移，天氣變得越來越暖了。 As spring warms the earth, al flowers begin to bloom. 隨著春回大地，百花開始綻放。 4when, while, as的用法區(qū)別 只有當(dāng)從句表示的是段時間，即其謂語動詞有持續(xù)性特征時，這三者可以通用互換。 I got the news on the radio when while as I was having breakfast. 我在吃早飯的時候從收音機里獲悉這一消息。 在下列情況下，三者彼此之間不能替換使用： aas更強調(diào)同一時間或緊接的一前一后或伴隨著的變化。 We listened to the singer sing as he played the guitar. 我們聽著歌星邊彈吉它邊演唱。 I thought of it just as you opened your mouth. 你一張嘴我就知道你要說什幺 As he grew older, he became less and less active. 隨著他年齡的增長，他變得越來越不活潑了。 提示： 狀語從句可放在主句之前或之后，放在主句之前時一般用逗號與主句分開。有時可置于主句中間，前后用逗號。 bwhen更強調(diào)特定時間，還可表示從句中的動作先于或后于主句的動作。 When I had given Mary the spare ticket, I found my own already gone. 當(dāng)我把多余的票給了瑪麗時，我才發(fā)現(xiàn)我自己的票已不知去向。（從句動作發(fā)生在主句之前，注意主從句的時態(tài)） When I finally got there, he meeting had been on for ten minutes. 當(dāng)我最終趕到那里時，會議已開始十分鐘了。（從句動作發(fā)生在主句之后，注意時態(tài)） cwhile從句只能表示延續(xù)的動作或狀態(tài)或主從句中動作的對比。 She thought I was talking about her daughter, while in fact, I was talking about my daughter. 她以為我在談?wù)撍畠海聦嵣?，我在談?wù)撐业呐畠骸?d若表示兩個短促動作幾乎同時發(fā)生時，用as場合多于when。 As he finished his speech, the audience burst into applause. 他結(jié)束講話時，觀眾爆發(fā)出雷鳴般的掌聲。 5whenever whenever是when的強勢語，它描述的不是一次性動作，而是經(jīng)常發(fā)生的習(xí)慣性動作。 You are always welcome whenever you come. 無論你何時來都?xì)g迎。 Whenever we met with diffiulties, they came to help us. 每當(dāng)我們遇上困難的時候，他們就來幫我們。B before, after 1before before表示在一段時間之前。 I must finish all the work before go home. 回家之前我必須干完所有的活。 You must first learn to walk before you try to run. 在想要跑以前，你得先學(xué)會走。 He had learned English for three years before he went to London. 他去倫敦之前已學(xué)了三年英語。 提示： before 從句往往帶有否定的含義。 He ran off before I could stop him. 我還沒來得及阻止他，他就跑掉了。 Thke it down berore you forget it. 趁著還沒忘記的時候就記錄下來。 必背： before 常用句型 It is was will be before It wil be five years before we meet again. 五年以后我們才能再見。 It will be not long before you regret what you have done. 不用過多久你就會對你所作所為感到后悔的。 It was not long before I realized I was wrong. 不久我就意識到我錯了。 It was minutes before the police arrived. 過了幾分鐘警察才到。 2after after表在一段時間之后。 Lets play football after school is over. 放學(xué)后我們踢足球吧。 The sun came out soon after the storm stopped. 暴風(fēng)雨過后不久，太陽出來了。 Ctill, until 1untiltill用于肯定句時，表示直到 為止，主句必須為持續(xù)性動詞。 We shall wait until till he comes back. 我們將一直等到他回來。 (注意它們的拼寫) Everthing went well untiltill that accident happened. 直到發(fā)生那意外之前，一切都正常。 2 notuntiltill表示直到 才 ，主句通常要用短暫動詞，這時until和till可用before代替。 I didnt leave until till before she came back. 直到她回來，我才離開的。 Bells dont ring till until you strike them. 鈴不打不響。 Peopl do not know the value of their health till until before they lose it. 人們直至失去了健康才知其可貴。 3當(dāng)not until位于句首時，主句中的主語、謂語要使用倒裝語序。 Not until she stopped crying did I leave. 直到她不哭了，我才離開的。 注意： until引導(dǎo)的從句可以放在主句之前或主句之后，但till從句一般不放在句首。 4在強調(diào)句型中一般只能用until，不用till。 It was not until she took off her drk glasses that I recognized her. 直到她摘下墨鏡，我才認(rèn)出她。 Dsince, ever since 1since自以來。表示動作從過去某一點時間一直延續(xù)到說話時間為止。主句中通常為延續(xù)性動詞的現(xiàn)在完成時，since從句中一般用短暫性動詞的一般過去時。 It has been just a week since we arrived here. 我們到這兒剛剛一星期。 Where haveyou been since I last saw you 自上次我見過你之后，你去了哪里？ Since she was young, she has been collecting stamps. 她自年輕時起就一直集郵至今。 提示： 有時since 從句中也可以用延續(xù)性動詞，注意它的譯法。 Tom is now working on the farm.Its two years since he was a college student. 湯姆現(xiàn)在農(nóng)場上班，他大學(xué)畢業(yè)已有兩年了。 2ever since 從那時起直至現(xiàn)在，此后一直。表示說話者強調(diào)主句動作或狀態(tài)持續(xù)時間長，語氣比since強。 Ever since they got married in 1950, they have lived happily. 自一九五零年結(jié)婚以來，他們一直生得很幸福。 3since還可以用作副詞或介詞。 The big clock was damaged during the war and has been sient（ever）since. 這只大鐘在戰(zhàn)爭中損壞了，從此就一直不響了。 My uncle went to Tibet in the 1950s. He has been living there（ever）since. 我叔叔五十年代就去了西藏，從那以后他一直生活在那里。 You have made great achievements in your work since graduation. 你們自畢業(yè)以來已經(jīng)在工作中取得了巨大成就。 Eas soon as as soon as.可譯為一就，用來表示主從句的動作是緊接著發(fā)生的。 He will come and see you as soon as he can. 他一有空就來看你。 He rushed home as soon as he got the good news. 他一得到這個好消息就奔回家。 必背： 一就還可以用onupon doing 結(jié)構(gòu)來表示。 On arriving home he called up Lester. = As soon as he arrived home, he called up Lester. 他一到家就給萊斯特打電話。 F immediately instantly directly 相當(dāng)于as soon as，從句中用一般過去時態(tài)。 They phoned her immediately they reached home. 他一到家馬上就給她打了電話。 I recognized her instantly I caught a glimpse of her. 我一看見她就把她認(rèn)出來了。 We came directly we got your telephone. 我們一接到你的電話就趕來了。 Gthe moment, the minute, the instant, the second 這幾個名詞短語也可用作連詞，直接引導(dǎo)時間狀語從句，表示一 就 。 He said hed turn on TV th moment he got home. 他說他一到家就打開電視機。 Tell him I need to see him the minute he arrives. 告訴他，他一到我就要見他。 The second the bell rang, the students rushed out of the classroom. 鈴一響，學(xué)生就沖出了教室。 Hhardly scarcelywhen, no soonerthan 這兩個短語都表示剛就，可以互換，主句通常用去完成時。 He had no sooner started out than he felt homesick. 他剛出發(fā)就想起家來。 He had hardly started his speech when someone rose to refute his points. 他剛開始發(fā)言，就有人站起來反駁他的論點。 注意： 當(dāng)hardly, scarcely, no sooner 位于句子的開頭時，主句須用倒裝語序。 Hardly had she fallen asleep when a knockat the door woke her up. 她剛要睡著，忽然敲門聲把她吵醒。 No sooner was the frost off the ground than the work began. 地上的霜一消散，人們就開始工作了。 Ionce once作連詞時，也相當(dāng)于as soon as，但它含有的條件意味更濃，它引導(dǎo)的從句較短。 Once you begin, you must continue. 一旦開了頭，你就應(yīng)當(dāng)繼續(xù)下去。 Once you see him, you will neer forget him. 你一旦見過他，就不會忘了他的。 Jnext time, the first time, the last time, every time 等 Be sure to call on us next time you come to town. 下次你進(jìn)城一定來看我們。 He left me a good impression the first time I met him. 我第一次見他時，他給我留下了好印象。 Every time I see him he looks miserable. 我每次見到他，他都是一付痛苦的表情。 The last time I spoke to Bob, he seemed happy enough. 上一次我見到他時，他看上去很開心。 Kby the time by the tine 也可以引導(dǎo)時間狀語從句，意為到 時為止，主句一般要用完成時態(tài)。 By the time he was fourteen, Einstein had learned advanced mathematics all byhimself. 愛因斯坦到十四歲時就自學(xué)完了高等數(shù)學(xué)。 (從句為一般過去時，主句要用過去完成時) I shall have finished my work by the time you return. 在你回來之前我將會做完我的活兒。(從句為一般現(xiàn)在時，主句要用將來完成時) 二、地點狀語從句 地點狀語從句通常由where, wherever（where的強勢語）和everywhere引導(dǎo)，是表示空間關(guān)系的狀語從句。A where where 在地方，去地方 Wuhan lies here the Yangtze and the Han River meet. 武漢位于長江和漢水匯合處。 Where there is a will, there is a way. 有志者，事竟成。 I found my books where I had left them. 我的書在我原來放的地方找到了。 Youd better make a mark where you have any questions. 哪兒有問題，你最好在哪兒做個記號。(這里where引導(dǎo)的從句不是定語從句) 注意： 在地點狀語從句之前，不要使用介詞。 【誤】You should put the book at where it was. 【正】You should put the book where it was. 你應(yīng)該把書放在原來的地方。 【誤】We should go to where we are needed most. 【正】We should go where we are needed most. 我們應(yīng)該到最需要我們的地方去。 B.wherever wherevr在任何地方，無論哪里 Wherever you go, you should do your work well. 不論到什么地方，都要把工作做好。 You may sit down wherever you like. 你愛坐哪兒就坐哪兒。 C.everywhere Everywhere they went, they were kindly receivd. 他們每到一處都受到了友好的接待。 三、原因狀語從句 原因狀語從句是表示原因和理由的從句。引導(dǎo)原因狀語從句的有as, because, since, now (that), considering that, seeing that等。 Abecause because因為 Because I like it, I do it. 因為我喜歡，所以我才干。 He couldnthave seen me, because I was not there. 他不可能見過我，因為當(dāng)時我不在那兒。 比較： because 和for的區(qū)別。 1for 是并列連詞，只用于連接表示原因的分句，因此不能用于句首。because表示原因時，可位于句首。 【誤】For he did not obey the rules, he was punished. 【正】Because he did not obey the rules, he was punished. 由于他不遵守規(guī)章制度，他受到了處。 2for 表示的是推斷解釋，because強調(diào)動作發(fā)生的直接原因。 It must have rained last night, for the ground is wet. 昨晚肯定下雨了，因為地面是濕的。（不可用because，因為地面濕不是天下雨的原因） The day breaks, for the birds are singing. 天亮了，因為鳥在叫。（不可用because，因為鳥叫不是天亮的原因） He went to bed early, because he was tired 由于他累了，所以他很早就上了床。（直接的理由） He must be tired, for he went to bed early. 他肯定累了，因為他很早就上了床。（間接的推斷） 3在強調(diào)結(jié)構(gòu)It iswasthat和關(guān)聯(lián)詞notbut 引導(dǎo)的原因狀語從句中，宜用because。 Its because he helped you that Im prepared to help him. 正是因為他幫助過你，所以我樂意去幫助他。 He decided to give up thechance of going abroad, not because he did not want to but because his wife was ill. 他決定放棄出國的機會，不是因為他不想去，而是因為他妻子病了。B since since 因為，既然。引導(dǎo)的從句大多置于句首，主從句的時態(tài)一般相同。 Since you have no licence, you are not allowed to drive. 因為你沒有駕駛執(zhí)照，所以不允許你開車。 Since you are al here, lets try and reach a decision. 既然大家都來了，咱們就設(shè)法做出一個決定吧。 Cas as 由于。一般多用于句首。 As she was ill, she didnt come to the party. 由于病了，她沒來參加晚會。 As he was not well enough, I had to go without him. 由于他身體欠佳，我只好不帶他去了。 As it rained, we all stayed at home. 由于下雨我們都呆在家里。C because, since, as 的區(qū)別 1because語氣最強，表達(dá)的是未知的新信息，一般置于主句之后，也可以放在主句之前，用逗號隔開。在回答why引導(dǎo)的特殊疑問句時，或在強調(diào)結(jié)構(gòu)It iswas that 和關(guān)聯(lián)詞not but 引導(dǎo)的原因狀語從句中，要用because。另外，because還常和副詞just, merely等連用。 2since 往往表示的是已知的客觀事實，或分析后的推理，引導(dǎo)的從句大多置于句首，主從句的時態(tài)一般相同。 3as 表示的理由最弱，只是對主句的附帶說明，重點在主句。as從句通常放在主句前。 Just because he doesnt complain, you must not suppose that he is satisfied. 你不可只因他不抱怨就以為他滿足了。 You shouldnt get angry only because some people speak ill of you. 你不該僅僅因為有些人說了你的壞話就生氣。 Since youre not interested, Iwont tell you about it. 既然你不感興趣，那我就不告訴你了。 As you are unable to answer perhaps we should ask someone else. 因為你不能回答，也許我們該問一問別的人。 注意： because等詞不能與 so連用。 【誤】Because he was careless, so he failed in the exam. 【正】Because he was careless, he failed in the exa. 由于他粗心，所以他考試不及格。 【正】He was careless, so he failed in the exam. 由于他粗心，所以他考試不及格。 Enow that now that 既然，因為。that可以省略。 Now (that) dinner is ready, go and wash your hands. 既然飯已好了，洗手去吧。 Now you mention it again, I do remember. 既然你又提起此事，我倒回想起來了。 Fconidering that, seeing that 這兩個詞和since, now that意思相近，都有鑒于 事實，考慮到 的意思。 Seeing that quite a few people were absent, we decided to put the meeting off. 由于好些人都沒到會，我們決定延期開會。(seeing 后面的that可以省略) Considering that they are just beginners, they are doing quite good job. 考慮到他們才剛剛學(xué)做，他們干得算很不錯的了。 Gnot that but that 這一結(jié)構(gòu)相當(dāng)于漢語的不是因為 而是因為。 Not that I dont like the film, but that I have no time for it. 不是因我不喜歡看這部電影，而是因為我沒有時間看。狀語從句（二） 四、目的狀語從句目的狀語從句是表示行為目的的從句。引導(dǎo)目的狀語從句的主要連詞有that, so，so that, sothat, in order that等，從句中常常使用一些情態(tài)動詞，如can, could, may, might, should等。Athat, so that，in order that表示為了，以便，一般放在主句之后。that語氣較弱，用的較少，多用so that。Lets take the front seats that we may se more clearly. 我們坐前排吧，這樣我們可以看得更清楚些。 Man does not live that he may eat, but eats that he may live. 人生存不是為了吃飯，而吃飯是為了生存。 They hurried so that they might not miss the train. 他們?yōu)榱瞬徽`火車，才急急忙忙的。 In order that everyone present might hear her clearly, she raised her voice again. 為了使在場的每個人都能聽清楚，她再次提高了聲音。 注意：當(dāng)主從句的主語一致時，so that和in order that引導(dǎo)的目的狀語從句可以轉(zhuǎn)換成相對應(yīng)的動詞不定式結(jié)構(gòu)。 We got upearly so that we would arrive in time. 為了能及時趕到，我們起得很早。 They hurried so that they might not miss the train. They hurried so as not to miss the train. 他們?yōu)榱瞬徽`火車，才急急忙忙的。 Betty saved money in order that she could uy a portable computer. Betty saved money in order to buy a portable computer. 貝蒂存錢是為了買一臺手提電腦。 Bin case, lest, for fear that 幾個短語都表示萬一，惟恐，含有否定的意義。 Better take more clothes in case the weather is cold. 最好多帶些衣服以防天氣會冷。 Take an umbrella in caseit rains. 以防下雨，帶把傘。 五、結(jié)果狀語從句結(jié)果狀語從句是表示事態(tài)結(jié)果的從句。引導(dǎo)結(jié)果狀語從句的連詞有：that, so (that), sothat, suchthat等。結(jié)果狀語從句通常置于主句之后。 Aso, that, so that 這三個詞都可以引導(dǎo)結(jié)果狀語從句。so that最為常用，so或that常用于口語或非正式文體中。 What has happened tha you look so worried 發(fā)生了什幺事，使你顯得如此擔(dān)心？ I didnt plan the work well, so thatso I didnt finish it in time. 我沒把工作計劃好，結(jié)果沒按時完成。（so that從句常用逗號與主句隔開） The room was packed with people, so that we couldnt get in. 房間里擠滿了人，我們進(jìn)不去。C so.that so.that 如此以致。其引導(dǎo)的果狀語從句有如下四種結(jié)構(gòu)： 1so + 形容詞副詞 + that-從句 The village is so small that it cannot be shown in the map. 這村子太小，所以這地圖上沒有。 The wind was so strong that we could hardly move forward. 風(fēng)刮得那么大，我們簡直寸步難行。 2so + 形容詞 + aan + 單數(shù)名詞 + that-從句It was so hot a day that tey all went swimming. 天是那么的熱以致他們都去游泳了。 He made so inspiring a speech that everybody got excited. 他發(fā)表了如此鼓舞人的演講以致大家都很激動。 3so + manyfew +復(fù)數(shù)名詞+ that-從句I have had so many falls that I am black and blue all over. 我摔了許多跤，以至于渾身青一塊，紫一塊。 He has so few friend that he often feels lonely. 他朋友很少，所以經(jīng)常感到孤獨。 4so + muchlittle +不可數(shù)名詞 + that-從句 I had so little money then that I couldnt even afford a used car. 我當(dāng)時囊中羞澀，甚至連一輛二手車都買不起。 He drank so much wine last night that he felt terrible. 昨晚他喝了那么多的酒，他覺得很不舒服。 5.在so + 形容詞副詞 + that-從句結(jié)構(gòu)中，如將so + 形容詞副詞位于句首，主謂語要倒裝。 So excited was he that she could not say a word. 他很激動，一句話都說不出來。 So loudly did he speak that even the people in the next room could hear him. 他說得很響，連隔壁的人都能聽見。D such. that such.that 如此以致。其引導(dǎo)的結(jié)果語從句有如下四種結(jié)構(gòu)：1such + aan + 形容詞 + 單數(shù)可數(shù)名詞 + that-從句 Jenny is such a clever girl that all of us like her very much. 詹妮是如此聰明的女孩，以至我們都非常喜歡她。 We left in such a hurry that we forgot to lock the door. 我們走得匆忙，把門都忘了鎖了。 2such + 形容詞 +復(fù)數(shù)名詞+ that-從句 He gave suchimportant reasons that he was excused. 他說出了這么重要的理由，得到大家的諒解。 They are such interesting novels that all of us want to read them. 這些是十分有意思的小說，大家都想看。 3such + 形容詞 + 不可數(shù)名詞 + that-從句 He made such rapid progress that the teacher praised him. 他的進(jìn)步很快，老師表揚了他。 H shut the window with such force that the glass broke. 他關(guān)窗子用了那么大的勁，玻璃都碎了。 提示：such+aan+形容詞+單數(shù)名詞結(jié)構(gòu)可以和so +形容詞+aan+單數(shù)名詞結(jié)構(gòu)互換。 He told us such a funny story that we all laughed. He told us so funny a story that we all laughed. 他給我們講了一個如此有趣的故事，大家都笑。 The story he told us was so funny that we all laughed. 他給我們講的故事是如此有趣，大家都笑了。E such that such that可以連用，意思是（是）這樣.以致。 Mothers answer was such that she didnt say yes and she didnt say no. 媽媽的回答就是這樣，既沒有同意也沒有不同意。 His anger was such that he lost control of himself. 他勃大怒，以致不能自制。 比較：such .that . 引導(dǎo)的是結(jié)果狀語從句。 such .as .引導(dǎo)的是定語從句（請參考第10章定語從句）。 She had such a fright that she fainted. 她嚇得昏了過去。 Luckily such earthquakes as can cause a lot of damage do no happen very often. 很幸運，這種破壞性很大的地震并不經(jīng)常發(fā)生。（關(guān)系代詞as在定語從句中作主語） 六、條件狀語從句。條件狀語從句是表示主句動作發(fā)生的前提或條件的從句。條件狀語從句分為真實條件狀語從句和非真實條件狀語從句（見第3章）。引導(dǎo)條件狀語從句的有if, unless, so as long as, as so far as, on condition that, in case, suppose, supposing等。條件狀語從句中的謂語動詞一般要用現(xiàn)在時或過去時代替一般將來時或過去將來時。 Aif if表示正面條件，意為如果。 If you ask hm, he will help you. 如果你向他請求，他會幫助你。 Difficulties are nothing if we are not afraid of them. 如果我們不怕困難，困難就算不了什么了。 If I do not understand what he says, I always ask him. 我不懂他的話時, 總是去問他。（if = when） 比較： if only和only if的對比。 if only 解釋但愿，要是就好了，表示一個不可能實現(xiàn)愿望，要用虛擬語氣。 only if 解釋只有，等于only on condition that，從句用陳述語氣。 Only if you heat ice, it turns to water. 只有當(dāng)你給冰加熱，它才會變成水。 If only I knew! 要是我知道該多好。 Bunless unless = if not, 表示反面條件，意思是如果不、除非。 They will go tomorrow unless it rains. 除非明天下雨，否則他們會去的。 （They will go tomorrow if it doesnt rain.） I wont let you in unless you show me your pass. 如果你不出示通行證，我就不讓你進(jìn)來。 （= I wont let you in if you dont show me your pass. ） 注意： if.not和unless通常是可以換用的。但在下列情況下，兩者是有區(qū)別的： 1unless多引導(dǎo)真實條件句，ifnot可以引導(dǎo)真實條件句或非真實條件句。 Hewont be able to pass the final exams unless he works hard. 除非他努力，否則就通過不了期末考試。 He wont be able to pass the final exams if he doesnt work hard. 如果他不努力，就通過不了期末考試。 He would pass the final exams if he worked hard. 要是他努力的話，他就會通過考試。（非真實條件句。含義是He doesntwork hard.） 2如果主句描述的是情感或情緒活動方面的內(nèi)容，ifnot結(jié)構(gòu)不能換成unless。如： Ill be quite glad if she doesnt come this evening. 她今晚如果不來我很高興。 3unless引導(dǎo)的狀語從句可用否定結(jié)構(gòu)，而ifnot引導(dǎo)的從句不可再用否定結(jié)構(gòu)。 Dont ask me to explain again unless you really dont understand. 不要再叫我解釋了，除非你真的不懂。 4uless能作為介詞使用，相當(dāng)于except，而ifnot不可以。 Nothing will come out of it unless disaster. 這種事除非引起災(zāi)禍之外不會有什么結(jié)果。 Cso long as, as long as, on condition that 這幾個短語意思差不多，都表示只要，條件是。 AsSo long as we dont lose heart, well find a way to overcome the difficulty. 只要我們灰心，我們就能找到克服困難的方法。 You may use the room on condition that so long as you clean it afterwards. 只要你用完后打掃干凈，你就可以使用這個房間。 D