高一英语:状语从句全攻略——时间、条件、原因、让步从句的引导词与用法
一、什么是状语从句
状语从句就是在复合句中充当状语的句子,用来修饰主句中的动词、形容词、副词或整个句子,说明动作发生的时间、地点、原因、条件、目的、结果等。状语从句由从属连词引导,从句有主语有谓语,但离开连词就不能独立成句。高一阶段要求重点掌握时间、条件、原因、让步、结果、目的等几类,其中前四类是考试的重灾区,我们逐一攻克。
二、时间状语从句
时间状语从句说明主句动作发生的时间,常用引导词有 when、while、as、before、after、until/till、since、as soon as、once、whenever 等。用法上有三个易错点。
第一,when、while、as 的区别。when 引导的从句动作可以是短暂性的,也可以是持续性的,主句从句的动作可以同时发生也可以先后发生;while 强调主从句动作同时进行,从句动词必须是延续性的;as 强调「一边……一边……」或两个动作同时变化。例如「When I got home, my mother was cooking」中 when 后是短暂动作;「While I was reading, he was watching TV」中 while 后是延续动作。
第二,until/till 的用法。主句动词是延续性动词(如 wait、stay、work)时用肯定式:「He worked until midnight」意为「他一直工作到午夜」;主句动词是短暂性动词(如 leave、start、arrive)时必须用否定式 not...until:「He didn't leave until midnight」意为「他直到午夜才离开」。not until 放在句首时主句要部分倒装,如「Not until midnight did he leave」。
第三,since 与现在完成时搭配。since 引导的时间状语从句用一般过去时,主句用现在完成时:「We have known each other since we were children」。as soon as、once 引导的从句用一般现在时表将来:「I will call you as soon as I arrive」。
三、条件状语从句
条件状语从句表示主句动作发生的条件,常用引导词有 if、unless、as long as/so long as、in case、on condition that、provided that 等。
最核心的考点是「主将从现」:主句用一般将来时(或祈使句、含情态动词),条件从句用一般现在时表将来。例如「If it rains tomorrow, we will stay at home」,不能说 If it will rain。unless 相当于 if...not,例如「You will fail the exam unless you work hard」等于「You will fail the exam if you don't work hard」。as long as 意为「只要」,表示唯一的条件:「As long as you keep trying, you will succeed」。
注意:如果 if 从句表示的是一种假设、不可能实现的条件,就要用虚拟语气,主从句的时态都要相应变化,这一点在第三册会系统学习,高一阶段先掌握真实条件句。
四、原因状语从句
原因状语从句说明主句动作发生的原因,常用引导词有 because、since、as、for、now that、seeing that 等,它们之间有语气强弱的差别。
because 语气最强,直接回答 why 提出的问题,是全句的语义重心,可以单独成句回答问题;since 和 as 语气较弱,表示「既然、由于」,原因往往是双方都知道的事实,常放在句首;for 是并列连词,表示补充说明的理由,不能放在句首。例如「Because he was ill, he didn't come to school」;「Since everyone is here, let's begin」;「The ground is wet, for it rained last night」。now that 意为「既然」,常与现在时态搭配:「Now that you have finished your homework, you can go out to play」。
五、让步状语从句
让步状语从句表示「虽然、即使、尽管」,最常用的引导词是 although、though、even if、even though、while、no matter + 疑问词、疑问词 + ever 等。
第一考点是 although/though 不能与 but 连用,但可以和 yet、still 连用。汉语说「虽然……但是……」,英语只能说「Although he is old, he is still strong」或「He is old, but he is still strong」,两个结构不能混用。第二考点是 even if 与 even though 的区别:even if 侧重「即使(未必发生)」,even though 侧重「尽管(事实如此)」。第三考点是 no matter + 疑问词与疑问词 + ever 的互换:「No matter what you say」等于「Whatever you say」。此外 as 引导让步状语从句时要倒装:「Young as he is, he knows a lot」意为「虽然他年纪小,但懂得很多」。
六、其余四类状语从句速览
结果状语从句用 so...that、such...that 引导,注意 so 后接形容词/副词、such 后接名词:「He is so young that he can't go to school」;「It is such a good book that everyone wants to read it」。目的状语从句用 so that、in order that 引导,从句中常有 can、could、may 等情态动词:「He got up early so that he could catch the first bus」。方式状语从句用 as、as if、as though 引导:「Do as I told you」;as if 后的从句常用虚拟语气:「He talks as if he knew everything」。地点状语从句用 where、wherever 引导:「Put the book where you found it」。
七、易混连词对比表
| 连词 | 类型 | 关键区别 | 例句 |
|---|---|---|---|
| when | 时间 | 从句动作可短暂可延续 | When I arrived, he was sleeping |
| while | 时间 | 强调同时,动词须延续 | While he was reading, she sang |
| because | 原因 | 语气最强,回答 why | I stayed home because I was ill |
| since | 原因/时间 | 既然;自从(主句完成时) | Since you ask, I will tell you |
| although | 让步 | 不与 but 连用 | Although tired, he kept working |
| unless | 条件 | 相当于 if...not | Unless you hurry, you will be late |
| as soon as | 时间 | 一……就(主将从现) | I will call you as soon as I get home |
| so that | 目的 | 从句常含情态动词 | He spoke loudly so that all could hear |
| so...that | 结果 | so 后接形容词/副词 | The box is so heavy that I can't move it |
八、例题精讲
例题一:选择填空——「We will go to the park ______ it doesn't rain tomorrow.」空格处应填 if 还是 unless?答案:if。「如果明天不下雨,我们就去公园」,条件用 if;若用 unless(除非),句子意思会变成「除非明天不下雨」——语法上正确,但与语境不符,做题时一定要结合句意。
例题二:改错——「Although he was very tired, but he went on working.」这句话错在 although 与 but 不能同时使用,应删去 but,改为「Although he was very tired, he went on working」,或保留 but 删去 although。
例题三:翻译——「直到妈妈回来,我才开始做作业。」注意否定转移:英语说「I didn't start my homework until my mother came back」,「直到……才」对应 not...until 结构,主句用短暂性动词的否定式,从句用一般过去时。
九、课后练习
基础题:用适当的连词填空。(1)__ it was raining, we went out for a walk.(2)I will tell him the news _ he comes back.(3)He didn't go to bed ___ 11 o'clock last night.
提高题:将下列句子译成英语:(1)虽然这个问题很难,但我相信我们能解决它。(2)只要你努力学习,你就会取得进步。(3)他起得很早,以便能赶上第一班公交车。
挑战题:用 so...that 与 such...that 各写一个句子描述「这个电影太精彩了,我们看了三遍」,并说明两条规则的适用条件。
参考答案:基础题:(1)Although/Though;(2)as soon as;(3)until。提高题:(1)Although the problem is difficult, I believe we can solve it.(2)As long as you work hard, you will make progress.(3)He got up early so that he could catch the first bus. 挑战题:The film was so wonderful that we watched it three times. / It was such a wonderful film that we watched it three times. so 后接形容词或副词,such 后接名词或名词短语。