名校版英语经典句型考点解析 if only和only if用法.docx

名校版英语经典句型考点解析if only和。nly if用法s if only可表示对现时或未来的愿望，也可表示与过去事实相反的愿 望，作"只要但愿，要是就好了"解。第一种用法：相当于as long as只要，连接2个句子，从句是条件状 语从句：There had to be an answer he was sure he could tease it out if only he had time.一定会有答案一他肯定，只要他有时间就一定能弄个清楚。If only it clears up,we7 II go.只要天一放晴，我们就去。第二种用法：要是就好了 ；如果就好了 "旦愿用来表达一个不可能实现的愿望或假设，句子多用虚拟语气，偶尔有时 也用陈述语气：开only she would co me!要是她能来就好了。If only she come early.要是她早点来就好了。If only I knew then what I know now.要是当初我就懂了我到现在才领悟的东西，该多好啊！我的小弟弟想知道星期天我父亲是否将带他去动物园.（宾语从句）当if后面接什么时态都可以时，if为是否的意思，句子为宾语从句.：He asked if I had left with you, and I said no.他问我是否和你一块儿离开的，我说不是。if可引导名词性从句作"是否"解,常放在ask, doubt, know, learn, see, wonder等动词后。四开引导条件状语从句与祈使句的转换：主语为you的条件状语从句还可与"祈使句+and/or+简单句句 式互换.例如：If you work harder,youf II pass the exam.= Work harder,and you1 II pass the exam.如果你努力学习，你会通过考试 的。If you donf t hurry up,you7 II miss the train.= Hurry up,or you; II miss the train.快点，否那么你会赶不上火车的。五.当if后面接一般过去时的动词时，那么是一种虚拟语气.:If I didn' t make that mistake, I wouldn7 t have suffered such a failure.注意虚拟语气主句和从句都为一般过去式，是对现在的或经常性动作的 虚拟：eg:If I was a bird ,1 could fly.（事实我不可能是鸟）If I didn7 t make that mistake, I wouldn7 t have suffered such a failure.If I got up early in the morning, I wouldnt miss the train.If you were a bird,you could fly.如果你是鸟，你就能飞行了。I should have talked to mother if I had thought of it.如果当初我想到了，我就和妈妈说了。If I were to ask him for a loanzwould he agree ?如果我向他借钱的话，他能同意吗？If it should rain tomorrow,the rally would be postponed.要是明天下雨，群众大会就会延期举行。If I were an architect,I'd redesign this house.如果我是建筑师，我会重新设计这房子。If it were up there, it would be easier to find.如果它在那儿，就会更容易被找到。If had anything happened, he would have let me know.如果当初发生了什么事，他会让我知道的。if引导条件状语从句，从句可为真实条件从句，也可为虚拟条件从句。如 为真实条件从句，谓语用陈述语气，表示可能性很大，作"假使 如果" 解，通常用一般现在时代替一般将来时；如果if从句中用will,表示意愿。 从句如为虚拟条件从句，谓语动词要用虚拟语气，表示可能性不大或与过 去事实相反，作"要是，假如"解。可指过去的情况,也可指现在和将来的 情况。指将来情况时可用were t。或should。在现代口语中，一、三人 称后常用was代替were。if引导的虚拟条件句中，助动词 were,should,had可以移至主语前。其虚拟语气用法如下:(-)表示与现在事实相反的假设，用一般过去时：If only she could marry me!她要是能嫁给我就好了。If only I were as clever as you.要是我像你一样聪明该有多好啊!If only I could have helped put matters right.要是我当时能帮着把错误纠正过来就好了。If only I knew her name.我要是知道她的名字就好了。If only I were rich.但愿我很富有。If only I could get some sleep, I would be able to cope.要是能睡上一会儿，我就能应付了。柯林斯高阶英汉双解学习词典She writes me often, if only to scold me because I haven't writtento her她常来信，即使仅仅为了责怪我还没回信给她。If only it were that simple!要是那么简单就好了！If only he could conceal his part in the accident要是他能够隐瞒住自己在这场事故中的责任就好了。If only I could be master of this subject.我多么希望能精通这门学科。If only someone could help me!有谁能帮助我就好了！If only he arrived in time.但愿他能及时赶到。Oh, if only he knew English!唉，要是他懂英语该多好啊！（二）表示与过去事实相反的假设，用过去完成时：If only we had arrived in time,we would,we would not have missed the train.如果我们及时到达,我们就不会错过火车了。If only he had been he re.要是他当时在这儿就好了。The pills might have helped him, if only he'd taken them regularly.他当时要是按时服药，也许可以对他有帮助的。牛津高阶英汉双解词典If only you had told me that some time ago要是你早些时候告诉我该多好啊！If only somebody had told us, we could have warned you.如果有人告诉了我们，我们就能事先提醒你。If only I had another chance.要是我再有一次机会就好了。Look at the trouble I am in! If only I had followed your advice.看看我现在的困境，要是我当时采纳你的建议就好了。If only my father had possessed an ounce of business sense要是我父亲有一点点经商的头脑就好了。If only you hadn't felt compelled to meddle.要是你没有觉得非插手不可就好了。Oh! If only I'd known earlier.暧，早知道就好了。摘自汉英大词典（三）表示与将来事实相反的假设,用would +动词原形If only it would stop raining.但愿雨快停下来。If only he would hold her close to him.要是他能将她拥入怀中就好了。If only the banks would lend money without limit!但愿银行能无限制地贷款！摘自柯林斯高阶英汉双解学习词典If only it would clear up soon!但愿天气赶快放晴。二、only if表示：唯一的条件是，只有在.的条件下（的时候）才放在句首，句子倒装：Only if the red light comes on is there any danger to employees.只有红灯闪亮时才有危及职工的险情。牛津高阶英汉双解词典Children are admitted only if accompanied by an adult.儿童必须有成年人陪同方可入场。Syria will attend only if the negotiations deal with issues of substance.只有在谈判涉及重大问题时叙利亚才会参加。The lawyer is paid only if he wins只有官司赢了才支付律师费。柯林斯高阶英汉双解学习词典Use a fire extinguisher only if you have been trained to do so只有经过i） I练后才使用灭火器。高考真题-2018天津So, everyone can have a good fortune only if he tries his best.所以，每个人只有拼尽全力才能获得好运。中考真题-2018衡阳Where the penalties are not a must, they should be imposed only if the facts of a case support it.非必须的处分只有在案件事实支持的情况下才应予以实施。四级真题-2015年经典句型解析if句型if作名词时意思是"条件，设想；不确定的情况"，作连词时意思是"（表 条件）如果；（表假设）要是，假如；无论何时；虽然，即使；（用于 间接疑问）是否；（用于礼貌问询）是否；当，每次；（与情态动词连 用）表婉转客气；这不是，要是多好；或许不；就算；尽管"。条件状语从句表示主句动作发生的条件.引导条件状语从句的连词 不多，最常用的引导词为开（如果）.切记：引导条件状语从句的开,不能用 whether来替换.例句:Please call me if he is at home.假如他在家，请给我打 。(2)You must see a doctor if you are ill.如果你生病了,就必须去看医 生。(3)Don' t go to the beach if it rains.倘假设下雨就不要去海滩了。(4)If it rains tomorrow,! won' t go there with you如果明天下雨的 话,我就不和你一起去那儿了。(5 ) Don't play computer games if you don't finish your homework.如果你没有完成作业，就不要玩电脑游戏。(6 ) If it rains(从句),1 will stay at home (主句).=1 will stay at home if it rains.如果下雨，我就呆在家里。(7 ) If you drive too fast ,you may have an accident=You may have an accident if you drive too fast.如果你开得太快，你可能会出车祸。(8 ) If you go with me, you shall be rewarded.如果你和我一起去, 你会得到奖励的。(9 ) If you will be so kind as to help us, we can finish by six.如果你愿意帮助我们，到六点时咱们就能完成了。二.条件状语从句的时态:L主句用一般将来时,条件状语从句用一般现在时表将来.如：例句(4)、 (6).当主句含情态动词时,条件状语从句用一般现在时.如：例句(2)、( 7 )、 (9)2 .当主句为祈使句,条件状语从句用一般现在时.如:例句Q)和 、(5 )三.正确区分开引导的条件状语从句和开引导的宾语从句 在宾语从句中开为是否，如表示“将来时,那么用将来时态，宾语从句般位于主句之后;而在条件状语从句中If的意思为"如果，主句用一 般将来时，从句用一般现在时表将来，且从句位置比拟灵活,可位于主句之 后也可位于主句之前.请比拟:If you keep on working hard at English,you can learn it well.如果你继续努力学习英语，你就能够学好它.(条件状语从句)My little brother wants to know if my father take him to the zoo on Sunday.