我们必须好好来学习知识。对此精品学习网初中频道编辑为大家整理了初中英语语法知识。详情如下：

连接词辨析

(1) because、as、since、for的用法：because(因为)表示原因的语气最强,常表示必然的因果关系,从句一般放在主句后面;另外,回答why的问句只能用because. as(因为)表示一般的因果关系,语气比because弱,说明比较明显的原因,它引导的从句可以放在句首也可以放在句尾。since(既然)表示对方已经知道、无需加以说明的原因或事实。for(因为)是并列连词,语气较弱,用来补充说明理由或提供一种解释。如：He is not at school today because he is seriously ill.(他今天没有上学因为他病得厉害)/ As all of you have got here, now, let’s go to the zoo.(既然大伙儿都到了我们就去动物园吧)/ I will ask Lin Tao to go with me since you are very busy.(既然你很忙我就叫林涛和我一起去吧)/ We must be off now for the match starts at 7：00.(我们得走了因为比赛在七点开始)

(2)if、whether的区别：表示“是否”时,if和whether同义,引导宾语从句,另外,whether还可以引导主语从句、表语从句(以及同位语从句)等名词性从句或者让步状语从句;而if还可以表示“如果”,引导条件状语从句,(主句与从句遵循主将从现的原则)。如：I don’t know if/whether he will arrive on time.(我不知道他是不是会按时到达)/ I will ring you up if he arrives on time.(如果他按时到达我会给你打电话的)

[注意]下列情况只能用whether不能用if：①引导主语从句,②引导表语从句,③引导从句作介词宾语,④引导不定式短语,⑤引导让步状语从句,⑥在动词discuss之后,⑦在wonder / not sure之后,⑧在if与whether含义易混时。如：Whether it is a fine day next Sunday is still a question.(下个星期天是不是个好天还是个问题)(引导主语从句) / Please ask him whether to go there with a raincoat or not.(请问一下带不带雨衣去那儿)(作动词的宾语) / Hainan is the place to be, whether it’s summer or winter.(海南是个该去的地方无论冬夏)(引导让步状语从句)/ Please let me know whether you need my help.(请告诉我你是否需要我的帮助)(引导宾语从句)(如果换成if则还可能表示“如果你需要我的帮助请告知”)

(3)while、when、as的用法区别：while常表示一个较长的动作,它引导的从句动作与主句的动作是同时发生的、是平行的;when可以表示较短的动作也可以表示较长的动作,主句和从句的动作可以同时发生也可以先后发生;as与上两词同义,可替换while和when, 表示主句和从句的动作同时发生,常译为“一边……一边……”。如：Please do not trouble me while I am writing my homework.(我写作业时请不要打扰我)/ I’ll go home when I have finished my job.(我干完了活儿就回去)/ They were running quickly across the road when they heard the sound of a truck coming.(他们正快速地穿过马路忽然听到了卡车开来的声音)/ As we walked in the dark street, we sang songs and talked loudly.(当我们在黑洞洞的街上走路时我们高声地唱歌说话)

(4)till/until与not…till/until的区别：前者表示一个延续性的动作,后者表示一个才开始的动作。如：I will stay here and watch the baby until you return.(我会呆在这里看着娃娃直到你回来)(stay这个动作一直进行到你return) / They won’t go on working until they get what they think is reasonable.(他们要到获得了他们认为合理的东西时才会继续干下去的)

另外till与until基本可以互换,但是在句首时只能用until,不能用till. 如：Until the last minute of the match we kept playing.(我们坚持到比赛的最后一分钟)/ Not until he had finished his work did he go home.(直到做完工作他才回家)(倒装句)

(5)though与although的区别：两个词都表示“虽然”,均不可以与but同时使用,但在句中可加still或yet连用。although“尽管、虽然”仅作连词,比较正式,一般可以换为though; though“虽然、尽管、即使”,还可以与even连用(=even if),表示“即使、纵然”,作副词时意思是“然而、不过”,不能放在句首。如：He passed the exams although illness prevented him from going to classes.(尽管疾病使他无法上课但是他还是通过了考试)/ she won’t leave the TV set,even though her husband is waiting for her for the supper.(她不愿离开电视机虽然丈夫在等她吃饭)/ It was a quiet party. I had a good time, though.(这是个不热闹的聚会尽管如此我还是玩得很开心)

(6)prefer to…rather than…与prefer…to…的区别：prefer to…rather than…后面都是用动词原形,prefer…to…都是用动名词或名词。如：I prefer English to Japanese.(与日语相比我更喜欢英语)/ I prefer to learn English rather than learn Japanese. (与日语相比我更喜欢学英语)

欢迎大家去阅读由小编为大家提供的初中英语语法知识大家好好去品味了吗?希望能够帮助到大家，加油哦!

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