中考语法专题条件状语从句（讲解+练习，无答案）
条件状语从句
常用引导词：if, unless, as/so long as
1、if 从句 + 祈使句，“如果……，就……”
If you do not feel well, please go to see the doctor. 如果你感觉不舒服，就去看医生 吧。
If you want to know more about it, call now. 如果你想了解更多内容，现在就打电话 吧。
Make sure you visit the Science Museum if you ever go to London. 如果你去伦敦，一 定要去参观科学博物馆。
2、主将从现
If I start after dinner, I’ll finish it before I go to bed. 如果我晚饭后开始，睡觉前我就能 完成。
主句也可用“情态动词 + 动词原形” She may come with us if she arrives in time. 如果她来得及时，就可以和我们一起去。
3、if 条件状语从句和并列句的转换
Hurry up, or you’ll be late. = If you don’t hurry up, you’ll be late. Study hard and you will pass the exam. = If you study hard, you will pass the exam. 练习 （一）句型转换 1. Run fast, or you’ll be late for school. _______ you _______ _______ fast, you’ll be late for school. 2. You can buy the dictionary if you take enough money with you. Take enough money with you, _______ _______ _______ buy the dictionary. 3. If there is no air, none of us can live. None of us can live _______ _______.
4、unless “除非”
Don’t leave the building unless I tell you to. 不要离开大楼，除非我准许。 Unless you have finished your homework, I won’t allow you to watch TV. 除非你已完成 了作业，否则我是不会让你看电视的。 unless = if not You’ll be late if you don’t hurry. = You’ll be late unless you hurry. I can’t catch the train if I don’t get up early. = I can’t catch the train unless I get up early.
练习
虚拟语气(一) 一、考点聚焦 1、虚拟语气用于条件状语从句中 If I were a boy, I would join the army. If she had time, she should go with you. If h e had taken my advice, he would have succeeded in the competition. If i t were to rain tomorrow, the football match would be put off. If I had time, I would attend the meeting. If he had hurried ,he could have caught the train. If I were to go abroad ,I would go to America 如果我是你，我就会努力学习 If I were you, I would work harder at my lessons. 如果我知道他的电话号码，我就给他打电话了 If I had known his telephone number, I would have called him. 如果明天下雨的话，我们会取消比赛． If it should \were to rain, we would call off the match.
使用虚拟条件句要注意的几点： １．当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，被称为：错综时间条件句“，动词的形式要根据它所表示的时间作出相应的调整． If you had followed my advice , you would be better now. 如果你听我的建议，你现在就会痊愈了． If you had studied hard before, you would be a college student now. 如果你努力学习的话，你现在就会是大学生了． If they had worked hard, they would be very tired now.(从句说的是过去，主句指的是现在) ２．省略句 在条件句中，可省略if，把were ,had, should 提到句首，变为倒装句式．If I were at school again, I would study harder. Were I at school again, I would study harder. If you had come earlier, you would have met him. Had you come earlier, you would have met him. If it should rain tomorrow, we would not go climbing. Should it rain tomorrow, we would not go climbing. Were I a boy, I would join the army. Had he taken my advice, he would have succeeded. Were it not for the expense, I would go to Britain. 2、虚拟语气用于名词性从句 （1）虚拟语气在宾语从句中的运用。 ①“wish + 宾语从句”表示不能实现的愿望，译为“要是……就好了”等。 表现在过去时 表过去过去完成时 表将来would, might, could＋动词原形 I wish it were spring all the year round. I wish I had known the answer. I wish I could fly like a bird. I wish (that) I were a bird. I wish (that) I had seen the film last night. I wish (that) I would\could go.
条件句逻辑与汉语条件句的解释 条件命题 P → Q 前件：antecedent 后件：consequent 条件连词：→（箭头） →真值表 Conditional (where P is the antecedent and Q, the consequent; or P is the protasis and Q, the apodosis): P→Q 111 100 011 010 Modus Ponendo Ponens (MPP) 肯定前件律 A,A→B┝B Modus Tollendo Tollens (MTT) 否定后件律 ~B, A→B┝~A (1)P → Q (2)~Q → ~P （contraposition 质位互换）
充分条件同（1） 必要条件： （3）Q → P 对（3）作质位互换，得（4） （4）~P → ~Q （同（3）的必要条件关系） 举例： （5）So long as we scatter it, thought force is of little use to us, but as soon as we are prepared to take the trouble necessary to harness it, all knowledge is ours. （6）只要使用这种洗涤剂，便可洗得干干净净。 (7) 只要把球传给队友，他们就能得分。 (8) 只要你脸蛋长得还算过得去，哪怕一个字也不认识，也照样能当演 员。 以上充分条件句 （9）Nothing terrible will befall if you eat a piece of pizza — only if you exist on a diet of nothing but pizza. (10) We all agree that small stores are important, but they can remain viable only if they can carry out their trading on Sundays.
条件句从句主句 真实一般现在时一般将来时 情态动词+动原祈使句 非真实 一般过去时 be动词用（were） would/could+动原初中英语――条件状语从句（讲解&练习） Ⅰ条件状语从句的定义 Ⅱ条件状语从句的引导词 1.if引导的条件状语从句：表示在某种条件下某事很可能发生。 If we pay much attention to the earth, we'll have a better world. 如果我们多关爱地球，就会拥有一个更美好的世界 If it rains tomorrow, what shall we do? 如果明天下雨，我们怎么办？ 注意：if还可以引导虚拟条件句，表示不可实现的条件，从句中多用一般过去时或过去完成时。 What would happen if there were no water ? 如果没有水会怎样？ 2.unless引导的条件状语从句，unless的意思是如果不，除非。可与if...not互换。 You will fail in English unless you work hard. 你英语考试会不及格的，除非你更加努力。 3.as /so long as引导的条件状语从句：as /so long as意思是“只要” So long as you're happy,i will be happy. 只要你高兴，我就高兴。 Ⅲ条件状语从句的种类 Ⅳ条件状语从句的时态原则 用法例句 ①主句为一般将来时态，if从句用一般 现在时态（即主将从现）。We will stay at home if it rains tomorrow. 如果明天下雨，我将要呆在家。 ②主句中含有情态动词，if从句用一 般现在时态。If you finish your homework, you can go home now.如果你做完了作业，你现在可以回家了。 ③主句为祈使句，if从句用一般现在 时态。Don’t jump into the river if you feel very hot. 如果你感到很热，不要跳入河里。 ④主句为过去将来时，if从句用一般 过去时态（如果涉及到be动词， 一律都用were）。此时，表达的是和现实相反的推测，用虚拟语 气。If I were you, I wouldn’t do it like that.如果我是你，我就不会那么做的。 If you gave me some money, I would be very happy. 如果你给我一些钱，我就会很高兴的。 二、if 引导的条件状语从句 （1）“if 从句+祈使句”的句子。其实，if 作为一个连词，主句也可以是其他形式的句子。 例如：If you want to go, please let me know. (2)“祈使句 + and (or)+ 陈述句”
if条件状语从句中的虚拟语气 一、if条件状语从句中虚拟语气的判断判断是真实条件句还是非真实条件句。 只有在非真实条件句中才使用虚拟语气。通过句子意思，看假设的条件是否能够实现， 能够实现是真实条件句，不能使用虚拟语气； 假设的条件不能实现则是非真实条件句，要用虚拟语气。 1. “后退一步法”后退一步法是指在准确地判断了该句与哪一事实相反后，按虚拟语气的后退一步法处理从句谓语动词的时态。即：在非真实条件状语从句中，谓语动词按正常情况“后退一步”。也就是： ①与过去事实相反，在从句中用过去完成时形式表示。 ②与现在事实相反，在从句中用过去一般时形式表示。 ③与将来事实可能相反，在从句中用过去将来时形式表示。主句中则用情态动词would, should, could 等加一个与从句一致的动词形式。 例：⑴、If I had come her yesterday, I would have seen him. ⑵、If I were a teacher, I would be strict with my students. ⑶、If it should snow tomorrow, they couldn't go out. 2、注意事项： ①if条件句中如有were, should, had，可以省去if，并使用倒装语序。 ②在现代英语中if条件状与从句中的谓语动词如果是be其过去形式一般用were。 二、虚拟语气在if 引导的条件句中的用法： 1. If it weren’t for your help, we would get into trouble. 如果没有你们的帮助，我们就会陷入困境。（而事实上得到了你们的帮助） 2.If the weather were fine, I would go there. 如果天气好，我去那儿。（事实天气不好） 3.If I were you, I would read it again. 如果我是你的话，我再读一遍。（事实上我不是你） 4.If time permitted, I would write it again. 如果时间允许的话，我再写一遍。（事实上时间不允许） 5.If it weren’t snowing, we wouldn’t stay in the house. 要是现在不下雪的话，我们就不会待在屋里。（事实上现在下雪） 6.What would I do if I were in your place?要是我处于你地位我会怎么办？（事实上我不在你的位置上） 7.If he hurried, he could catch the first bus. 他要是快点能够赶上头班公共汽车。（可是他不着急） 8. If I were you, I should buy it. (从句用过去式动词were，主句用动词原形buy) 9. If I had time, I would study French. (如果有时间，我会学习法文。)（从句用过去式动词had，主句用动词原形study） 10. If she knew English, she would not ask me for help. (如果她懂英文，她就不必要我帮了。)(从句用过去式动词knew, 主句用动词原形ask) 注意：如果动作在进行中，主句要用："主语+ would be + 进行式动词+ ……" 14. If they were here, he would be speaking to them now. (从句用过去式动词were, 主句用would be speaking)
指示條件句 指示條件句(indicative conditionals)是條件句的一種，其與虛擬條件句(subjunctive conditionals)在英文裡都具有”If…then…”這樣的句型，而它們之間的差別則在於動詞的語氣（mood）上。指示條件句與虛擬條件句在動詞語氣上的不同，並不意味著兩者非得有不同的語意論(semantics)不可。有些哲學家，如M. Woods和R. Stalnaker，便認為這兩者的差異其實是在語用(pragmatics)而非在語意上，但也有一些哲學家，如D. Lewis和F. Jackson，則認為它們是兩種在語意上截然不同的條件句。我這次演講的焦點集中在指示條件句的語意論以及這兩種條件句的關聯之上。 指示條件句的語意論自古以來即有爭議；有關指示條件句語意上的爭論至少可以追溯至斯多葛(Stoics)時期。根據Sextus Empiricus的說法，斯多葛學派中就有四種關於指示條件句語意論的看法：(1) Philo認為指示條件句中的”If…then…”為真值函數的連接詞；”If P then Q”在前件真而後件假時為假，在其他的情形下則為真。(2) Philo的老師Diodorus則認為指示條件句所表達的是涉及時的全稱性命題；”If P then Q”為真的條件是：在過去、現在和未來中，沒有任何時間裡P為真而Q卻為假。(3) Chrysippus認為”If…then…”為非真值函數的連接詞；”If P then Q”這樣的條件句表達了某種其前件與後件間在容貫性上的關聯：”If P then Q”為真若且惟若肯定其前件而否定其後件會導致不一致。(4) 最後，當時還有一些哲學家(已無法考據是誰)反對前述三種看法，他們認為，”If P then Q”這樣的條件句為真若且惟若Q在實質上「被包含在」(included)前件中。 對於這四種看法，我們可以用當代的邏輯符號來加以重新表述如下：(1) Philo認為”If P then Q”的意思就是”P ?Q”，其中”?”代表實質蘊含(material implication)；(2) Diodorus認為”If P then Q”的意思是”(t)(P is true-at-t ? Q is true-at-t)”，其中”t”是時間變數；(3) Chrysippus認為”If P then Q”的意思是”□(P ?Q)”，其中”□”代表「必然地」這個模態詞；(4)至於其他主張「包含」關係的學者，因其文獻早已喪失且「包含」一詞語意過於含混，已無法精確地用當代術語來加以表示。 中世紀哲學家們延續了斯多葛時期對條件句的討論，但問題似乎從「指示條件句的語意論為(1)至(4)中的哪一個？」轉移到「是否有好幾種在語意上不同的指示條件句？」這個問題之上。比方來說，Boethius便似乎認為至少有兩種不同的指示條件句，一種斷言其前後件間有某種必然性的關聯，另一種則否。但中世紀學者對指示條件句的討論過於晦澀，並且他們的討論與當時哲學家們對consequentia的看法夾雜不清。因而這些討論雖然有趣，成果卻不豐碩。 廿世紀對指示條件句語意論的主流立場基本上是回到了Philo的主張：”If
if引导的条件句中的虚拟语气 虚拟语气表示一种不能实现的假设。该语法主要用于if条件状语从句。 一、if引导的条件状语从句的分类及虚拟条件句的判断 1、可以把条件句分为两类： 1).真实条件句（Sentences of Real Condition）：凡是假设的情况发生性可能很大，就是真实条件句。例如： ⑴、If I have time , I will help you with this work.如果我有时间会帮助你做此工作的。 (2)、If time permits, we'll go fishing together.(如果有时间的话，我们就一起去钓鱼。） 2).虚拟条件句（Sentences of Unreal Condition）：当假设是不大可能实现时，就是虚拟条件句。例如： ⑴、If I were you , I would have attended the meeting. 如果我是你的话，就去参加会议了。 ⑵、If he had come here yesterday, he would have seen his ol d friend.假如他昨天来这儿的话，就会看见他的老朋友。 ⑴、If it had rained yesterday, we would have stayed at home.（如果昨天下雨的话，我们就会留在家里。） 2、.if条件状语从句中虚拟语气的判断 判断是真实条件句还是非真实条件句。只有在非真实条件句中才使用虚拟语气。通过句子意思，看假设的条件是否能够实现，能
够实现是真实条件句，不能使用虚拟语气；假设的条件不能实现则是非真实条件句，要用虚拟语气。 判断这个假设是与哪个事实相反。通常有三种情况：①与过去事实相反。②与现在事实相反。③与将来事实可能相反。 3、“后退一步法” 后退一步法是指在准确地判断了该句与哪一事实相反后，按虚拟语气的后退一步法处理从句谓语动词的时态。即：在非真实条件状语从句中，谓语动词按正常情况“后退一步”。也就是： ①与过去事实相反，在从句中用过去完成时形式表示。 ②与现在事实相反，在从句中用过去一般时形式表示。 ③与将来事实可能相反，在从句中用过去将来时形式表示。 主句中则用情态动词would, should, could 等加一个与从句一致的动词形式。例： ⑴、If I had come her yesterday, I would have seen him. ⑵、If I were a teacher, I would be strict with my students. ⑶、If it should snow tomorrow, they couldn't go out. 4、注意事项 ①if条件句中如有were, should, had，可以省去if，并使用倒装语序。 ②在现代英语中if条件状与从句中的谓语动词如果是be其过去形式一般用were。
条件状语从句讲解 ――if引导的条件状语从句（注意&练习）在句子中做条件状语的从句称为条件状语从句。可置于句首、句尾，有时还可置于主语和谓语之间。引导条件状语从句的连接词有：if ,unless,as/so long as等 1.if引导的条件状语从句 表示在某种条件下某事很可能发生。 If we pay much attention to the earth, we'll have a better world. 如果我们多关爱地球，就会拥有一个更美好的世界 If it rains tomorrow, what shall we do? 如果明天下雨，我们怎么办？ 注意：if还可以引导虚拟条件句，表示不可实现的条件，从句中多用一般过去时或过去完成时。What would happen if there were no water ? 如果没有水会怎样？ 2.unless引导的条件状语从句 unless的意思是如果不，除非。可与if...not互换。 You will fail in English unless you work hard. 你英语考试会不及格的，除非你更加努力。 3.as /so long as引导的条件状语从句 as /so long as意思是“只要” So long as you're happy,i will be happy. 只要你高兴，我就高兴。 4.once引导的条件状语从句 once引导的条件状语从句，意为“一旦...，就”，从句可置于主句前或后 Once you begin,never stop. 一旦开始，就绝不要停止 Maths is easy to learn once you understand the rules. 一旦你理解了规则，数学就不难学了。
iｆ引导的条件句中的虚拟语气?虚拟语气表示一种不能实现的 假设。该语法主要用于if条件状语从句。?一、ｉｆ引导的条件状语从句的分类及虚拟条件句的判断 1、可以把条件句分为两类： 1)．真实条件句（Sentences of Real Coｎdition）：凡是假设的情况发生性可能很大,就是真实条件句。例如:?⑴、If I ｈaｖe timｅ, I wｉll help yｏｕwith ｔhisｗork.如果我有时间会帮助你做此工作的。 (２)、Iｆtimｅperｍiｔs，ｗｅ＇ll go fishｉng tｏgetheｒ. (如果有时间的话，我们就一起去钓鱼。) 2).虚拟条件句（Seｎtｅnces of UnrｅaｌCoｎditiｏn):当假设是不大可能实现时，就是虚拟条件句。例如: ⑴、ＩfＩｗｅrｅyou ,I woｕｌd haｖe ａttenｄｅd th e meｅtiｎｇ．如果我是你的话，就去参加会议了。?⑵、I f ｈe had come ｈeｒe yesterday, ｈｅwouｌd haｖe sｅen ｈis ｏlｄfriｅnd.假如他昨天来这儿的话,就会看见他的老朋友。?⑴、If iｔｈaｄrained yｅsｔerday, we would hａve stayｅｄaｔｈｏme．(如果昨天下雨的话,我们就会留在家里。)?２、．ｉf条件状语从句中虚拟语气的判断?判断是真实条件句还是非真实条件句。只有在非真实条件句中才使用虚拟语气。通过句子意思，看假设的条件是否能够实现，能够实现是真实条件句，不能使用虚拟语气；假设的条件不能实现则是非真实条件句，要
用虚拟语气。?判断这个假设是与哪个事实相反。通常有三种情况:①与过去事实相反。②与现在事实相反。③与将来事实可能相反。 3、“后退一步法”?后退一步法是指在准确地判断了该句与哪一事实相反后，按虚拟语气的后退一步法处理从句谓语动词的时态。即：在非真实条件状语从句中,谓语动词按正常情况“后退一步”。也就是:?①与过去事实相反，在从句中用过去完成时形式表示。 ②与现在事实相反，在从句中用过去一般时形式表示。 ③与将来事实可能相反，在从句中用过去将来时形式表示。?主句中则用情态动词wｏuld, sｈouｌd, coulｄ等加一个与从句 一致的动词形式。例： ⑴、Ｉf I had coｍe ｈeｒyestｅrdａy，Ｉｗoｕlｄhave seen hiｍ. ⑵、Ｉf Ｉwｅｒe a teaｃhｅr, I ｗｏｕｌd bｅｓtrｉct wｉth my studenｔｓ. ⑶、Ｉｆit ｓhouｌd snow ｔomorｒow,ｔheｙcoulｄn't g o out. 4、注意事项?①iｆ条件句中如有ｗere，should, haｄ,可以省去if，并使用倒装语序。?②在现代英语中ｉｆ条件状与从句中的谓语动词如果是be其过去形式一般用wｅrｅ。 二、虚拟语气在ｉf 引导的条件句中的用法:?(一）、表示与现在事实相反的情况。其句子结构为：?从句:if + 主语+动词的过
1．常用引导词：if（如果），unless（除非）。 I won’t go to the movies unless I am free tomorrow. 除非我明天有空，否则我不会去看电影。 2．条件状语从句的位置 可放在句首或句尾，放在句首时常用逗号与主句隔开。 it rains tomorrow, I will stay at home. = I will stay at home if it rains tomorrow. 如果明天下雨我就呆在家里。 3．if引导词用法 if引导的条件句有：真实条件句和非真实条件句两种。 真实条件句：表示在某种条件下某事很可能发生。 you ask him, he will help you. 如果你请他帮忙，他会帮你的。 4．unless引导词用法 固定搭配：unless=if...not 除非，若不，如果不 will fail to arrive there in time unless you start earlier. =If you don’t start earlier, you will fail to arrive there in time. 如果你不早点动身，你就不能及时赶到 那儿。 注意：在含有条件状语从句的复合句中，当主句是一 般将来时态，从句要用一般现在时（即主将从现原 则）。如果主句是祈使句或含有情态动词时，从句也 用一般现在时表将来。
you study hard, you will pass the exam. 1. I will send you an e-mail as soon as I ____ A___ in Canada. A. arrive B. arrived C. am arrivi ng D. will arrive 2. If there ____A___ no buying and selling of an imals, there ______ no killing in nature. A. is; will be B. will be; will be C. is; is D. will be; is 3. I’m waiting for my , I'll go shopping alone. A. If she comes B. If she won't come C. If she doesn't come 5. You can’t watch TV ___A_____ you finish your homework. A. unless B. if C. while D. as students _____A___ have a sports meeting this we
条件状语从句 条件状语从句是一种比较常见的状语从句，引导条件状语从句最常用的连词是 if, 由if引导的条件状语从句表示在某种条件下某事很可能发生。如： If you ask him, he will help you. 如果你请他帮忙, 他会帮你的。 If you fail in the exam, you will let him down. 另外, if从句还表示不可实现的条件或根本不可能存有的条件, 也就是一种虚 拟的条件或假设, 从句多用一般过去时或过去完成时。如： If I were you, I would invite him to the party. I would have arrived much earlier if I had not been caught in the traffic. 如果没有堵车, 我会到的早一点儿。 其他的连词： 1.unless conj. 除非, 若不, 除非在…的时候 You will fail to arrive there in time unless you start earlier. 如果你不早点动身, 你就不能即时赶到那儿。 Unless it rains, the game will be played. 除非下雨, 比赛将照常实行。 2. on condition (that)...在……条件下, 如果; on condition (that)...引 导的条件从句是主句事件发生的前提条件或唯一条件。 I can tell you the truth on condition that you promise to keep a secret. 我能够告诉你真相, 条件是你答应保守秘密。 You can go swimming on condition (that) you don’t go too far from the river bank. 你只有在不远离河岸的条件下才能够下水游泳。 3. supposing conj. 如果, 假如 supposing引导的条件从句表示一种假设条件 Supposing it rains, shall we continue the sports meeting?
虚拟语气是一项语法难点，为了让学员们便于理解与记忆，我们把虚拟语气分成三大块来讨论： 1．名词从句中的虚拟语气标志词+should+动词原形 2．条件从句中的虚拟语气①三种基本态②倒装虚拟句③混时虚拟句④含蓄虚拟句⑤跳层虚拟句 3．其它情形中的虚拟语气（wish/would rather/It’s high time…/If only…/lest） 一．三种基本形态（1） 表虚拟的时间if从句谓语形式主句谓语形式 现在：did / were would (should, might, could)+do 过去：had done/ had been would (should/might/could)+have done(been) 将来：were to/ should+do would (should, might, could)+do 三种基本形态（2）（这是基础，建议牢记下面的例句，争取能脱口而出） 与现在事实相反：If I had enough money, I would buy a book. 与过去事实相反：If I had had enough money, I would have bought a book. 与将来事实相反：If I were to have enough money, I would buy a book. If I should have enough money, I would buy a book. 二、倒装虚拟句（只能与过去/将来事实相反，省去if，只有三种倒装形式）Had I had enough money, I would have bought a book. Were I to have enough money, I would buy a book. Should I have enough money, I would buy a book. 三、混合时间虚拟语气（主要是抓住时间状语） (对过去事实虚拟+对现在事实虚拟) If I had studied English at school, I could read the English novel now. (对现在事实虚拟+对过去事实虚拟) If she were not so careless, she wouldn’t have made such a mistake. 四、含蓄虚拟句（在四级考试中目前还未出现此考点，但在阅读中常见） 3. 虚拟语气用在主语从句中。在句型“It is important (necessary, strange, natural等) that...” 中，that 后面的从句中的谓语动词用(should) + 动词原形。It's necessary that we should have a walk now. 我们现在有必要出去散散步。What would I have done without you? But for their help, I would not have finished the task. But that the doctor arrived on time that day, they would have been dead. Given more time, I would have been able to finish the test.
Zero Conditional 零条件句 主谓模块 ? If people eat too much, they get fat. 如果人们吃得太多，就会发胖。 ? If you touch a fire, you get burned. 如果你碰了火，你会被烧伤的。 ? People die if they don't eat. 人不吃东西就会死。 ? Snakes bite if they are scared. 蛇害怕就会咬人 ? If babies are hungry, they cry. 如果婴儿饿了，他们会哭。 用法总结 This conditional is used when the result will always happen. So, if water reaches 100 degrees, it always boils. It's a fact. I'm talking in general, not about one particular situation. 当结果总是会发生时使用零条件句。所以，如果水达到100度，它总是沸腾。这是一个事实。这里指的是一般的正常情况，不是某个特定的情况。 The 'if' in this conditional can usually be replaced by 'when' without changing the meaning. 此条件中的“if”通常可以替换为“when”，其含义不变。 For example: If water reaches 100 degrees, it boils. (It is always true, there can't be a different result sometimes). 例如： 如果水达到100度，就会沸腾。 （这是一个科学事实）。 If I eat peanuts, I am sick. (This is true only for me, maybe, not for everyone, but it's still true that I'm sick every time I eat peanuts). 如果我吃花生，我就生病。 （只有我才是这样，也许不是每个人都是这样，但每次吃花生我都会生病）。The difference between the first and the zero conditionals is that the first conditional is about a specific situation, but the zero is talking in general. 第一条件句和零条件句的区别在于，第一条件句是关于一个特定情况的，而零条件句是指一般情况。
初中英语条件状语从句语法详解 (名师剖析语法知识点+ 实战训练题，值得下载打印) 一．条件状语从句的概念 条件状语从句，即在某种条件下，一件事情可能发生。在英语中由连接词if或unless等 引导的状语从句叫做条件状语从句。条件是指某一件事情实现之后（状语从句中），一件事 情（主句）才能发生，通常译作“假如，只要，如果”等意思。条件状语从句中，主从句的时 态要遵循“主将从现”的原则。即，主句是将来时态时，从句用一般现在时代替将来时态。 二.条件状语从句的引导词 1.If conj . 如果，假如 If you ask him，he will help you．如果你请他帮忙，他会帮你的。 If you fail in the exam，you will let him down．如果你考试不及格，你会让他失望的。 2.unless conj.除非,若不,除非在……的时候（if ...not...） You will fail to arrive there in time unless you start earlier. 如果你不早点动身,你就不能及时赶到那儿。Unless it rains, the game will be played. 除非下雨,比赛将照常进行。 3.so/as long as conj.只要 You may borrow my book as long as you keep it clean. 只要你保持书的清洁，你就可以把我的书借去。 三．关于条件句的时态，常见的有以下三种情况： 1、条件状语从句的主句是一般将来时，那么从句常常用一般现在时。 When I grow up, I’ll be a nurse and lo ok after patients. 我长大后要当一名护士，照顾病人。 2、如果主句是祈使句，那么从句通常要用一般现在时。 If you want to have a chat ,call me up. 如果你想聊天，打我电话。
条件状语从句 概念定义 由引导词if或unless引导的状语从句叫做条件状语从句。在英文中，条件是指某一件事情实现之后（状语从句中的动作），其它事情（主句中的动作）才能发生，通常译作“假如”。（注意：在含有条件状语从句的复合句中，表示将来时态，主句是一般将来时态,祈使句或情态动词，从句要用现在时态,[主将从现原则]（主将从现，将并非指将来时，还指表示将来含义的，跟着if后的那句话是从句。） 类型 条件状语从句 语法引导条件状语从句最常用的连词是if,由if引导的条件状语从句表示在某种条件下某事很可能发生。如： 1） If you ask him,he will help you. 如果你请他帮忙，他会帮你的。 2） If you fail in the exam,you will let him down. 如果你考试不及格，你会让他失望的 if引导的条件状语从句既可以将从句放前面也可以将从句放后面 （如果天下雨，我们就不玩了）If it rains,we will stop playing.‘ 转为We will stop playing if it rains. if引导的条件状语从句
另外，if从句还表示不可实现的条件或根本不可能存在的条件，也就是一种虚拟的条件或假设，从句多用一般过去时或过去完成时。如：If I were you,I would invite him to the party.如果我是你，我会邀请他参加聚会。I would have arrived much earlier if I had not been caught in the traffic.如果没有堵车，我会到的早一点儿。 那么，除了if之外，是否还有其他连词也可以引导条件状语从句呢?回答是肯定的，不仅有，还有很多。这些词由于出现的频率较小，且用法较复杂一些，所以不如if为大家所熟知罢了。下面就这些词的用法以例句的形式进行一下简单总结。 1、unless conj.除非，若不，除非在……的时候 You will fail to arrive there in time unless you start earlier.如果你不早点动身，你就不能及时赶到那儿。 Unless it rains,the game will be played.除非下雨，比赛将照常进行。 2、on condition(that)...在……条件下，如果 on condition (that)...引导的条件从句是主句事件发生的前提条件或唯一条件。 I can tell you the truth on condition that you promise to keep a secret.我可以告诉你真相，条件是你答应保密。 You can go swimming on condition (that) you don't go too far from the river bank.你只有在不远离河岸的条件下才可以下水游泳。 3、supposing conj.如果，假如 supposing引导的条件从句表示一种假设条件。 Supposing it rains,shall we continue the sports meeting?倘若下雨，我们的运动会还要继续举行吗? Supposing anything should go wrong,what would you do then?假如出了什么问题，你准备怎么对付?