状语从句指句子用作状语时,起副词作用的句子。
它可以修饰谓语、非谓语动词、定语、状语或整个句子。
根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。
状语从句一般由连词(从属连词)引导,也可以由词组引起。
从句位于句首或句中时通常用逗号与主句隔开,位于句尾时可以不用逗号隔开。
一、时间状语从句要点 : 时间状语从句,由以下连词引导:when while as after before as soon as since till /until by the time 在时间状语从句中,要注意时态一致。
一般情况下主句是将来时的时候,从句要用一般现在时。
当。
的时候mozart started writing music when he was four years old.(当 )莫扎特的时候,开始写音乐作品。
当。
时he visited a lot of places while he was traveling.他在旅途中参观了许多地方。
在。
的同时;一边。
一边。
he smiled as he stood up.他一边站起来一边笑着。
在。
之后he left the classroom after he had finished his homework the other day.前几天做完作业之后回的家。
在。
之前mr. brown had worked in a bank for a year before he came here.布朗先生来这之前已经在一家银行里工作一年了。
soon as 一。
就。
we began to work as soon as we got there.我们一到那就开始工作。
i will write to you as soon as i get home.我一到家就给你写信。
自。
以来到现在表示自过去的一个起点时间到目前 (说话时间 )为止的一段持续时间。
主句一般用现在完成时,从句用一般过去时。
mr green has taught in that school since he came to china three years ago.自格林先生来中国以来,他就在这所学校教书。
(还可以用作介词,本句从句还可以用短语:since three years ago(自三年前以来 )表示。
)8 till /until都可以作连词,连接时间状语,也可以作介词,与其它词构成介词短语,在句中作状语。
they walked till /until it was dark.他们一直走到天黑。
xiao ming didn’t leave home till / until his father came back.小明直到他爸爸回来才离开家。
9.by the time 到。
为止 (所在句子的主句应用完成时 ) bythe time he gets there , his father has already gone.他到家的时候,他爸爸已经走了。
by the time i got to school, the class had already began.我到校时,已经开始上课了。
难点——as when while 的辨析as when while 都表示主、从句动作同时发生,三者差异如下:表示“一边。
一边"的意思as 强调两个动作同时进行,并表示对比时用于发生时间较段时when 1、还可以表示从句动词的动作在主几句动词的动作"之前"或"之后"发生。
2、when=and then; at that moment ( 正在那个时候 )while 1、用于时间较长时2、强调两个动作同时进行,并表示对比时有时这三个连词可以互换,有时不可以。
lit was raining hard when (as) i got there.我到那里时,正在下大雨。
( 动作同时发生, when 可换为 as, 但不能换为while,因为 get 是点动词 .)lwhen i had read the article, he called me.我看完这篇文章之后,她给我打了电话。
( 从句动作发生在主句之前,注意时态表达,只能用 when )lwhen i got to the cinema, the film had begun.(当 )我到了电影院时,电影已经开演了。
(从句的动作发生在主句之后,只能用when,并要注意时态 )lhe was about to leave, when the telephone rang.他正要离开,忽然电话响了。
( 此时不能放在句首。
主句动词一般表达“正在”即“将”.while, as 不能代替) 考点lshe thought i was talking about her daughter, while, in fact, i was talking about my daughter.他以为我在谈她女儿,然而,实际上在谈论我女儿。
(表转折,对比, when, as 都不能代替它 ) 考点lwhile the alien was buying a souvenir, the girl called the police.外星人买纪念品时,那女孩给警察打了电话。
(表示主句,从句的动作同时发生,while 后引导的状语从句的动词必须是延续动词不能是点动词,因为它表示较长时间 )考点lmother was worried because little alice was ill, especially as (when/ while) father was away.妈妈担心,因为小爱丽丝病了,特别是他父亲不在家的时候。
(此时 as ,when, while 可通用 )知识扩展1. it is since从。
以来多长时间了(因为 since +从句或名词,表示一段时间)it is five years since we met last time.从我们上次见面已经五年了。
2. it is +before。
⋯(才)it was a long time before i went to sleep again.过了很长时间我才睡着。
it was an hour before(=until) the police arrived.过了一个小时,警察才来。
二、条件状语从句要点:表示状语从句由连词if, unless (=if not) 引导。
it doesn’t rain tomorrow, we will go hiking.如果明天不下雨 , 我们就去远足 .will get good grades if you study hard.如果你努力学习 ,就会取得好成绩 .will go to the party unless he goes there too.我不会去参加聚会的 , 除非他也去 .(如果他不去 ,我也不去 .)will be late unless you leave immediately.如果你不马上走 ,你将会迟到的 .(=if you don’t leave immediately, you will be late.)难点提示:用条件状语从句时要注意时态的正确使用,当主句是将来时的时候 ,从句要用一般现在时 .lhe will not leave if it isn’t fine tomorrow.一般将来时,一般现在时lthey are going to have a picnic if it doesn’t rain next week.一般将来时 , 一般现在时考点三、原因状语从句要点 : 由连词 because, since, as引导 , 也可由 for, now that等词引导didn ’t go to school yesterday because i was ill.我昨天没去上学,因为我生病了。
2. since everybody is here, let’s begin our meeting.既然大家都来了 , 让我们开始开会吧 .3. as you are in poor health, you should not stay up late.既然你身体不好 , 你就不该熬夜 .asked her to stay to tea, for i had something to tell her.我请她留下来喝茶 ,因为我有事要告诉她 ..难点——because , since , as , for,辨析在语气上, because 最重 , 表示的是直接理由 ,回答 why 时只能用它 . 其次是since, as 一,般不表示原因 , 而是表明理由 , 进一步说明 .(译为:由于,既然 ). for 被认为是复合句的并列连词 (常用于推断 ),表示理由 .四、地点状语从句要点 : 由连词 where 和复合关系词 wherever (=no matter where )引导 .知识扩展there is a will , there is a way.有志者事竟成。
(谚语 )will be mixed school where not all the children are disabled.他将是一所混合式学校,那里的儿童并不都是残疾。
(在限定性定语从句中对限先行词起限定作用。
)you go , i go too.无论你到什么地方,我都去。
(wherever=no matter where) 无论何处,多用于句首。
there is smoke , there is fire.无风不起浪。
(谚语 )4. while she was wondering where to go , she met a policeman.疑问副词 where 后跟不定式 ,构成不定式短语 . 考点五、目的,结果状语从句要点:目的状语从句由连词that, so that, so⋯that , in order引that导。
结果状语从句由连词 ( so )that, so⋯that, such⋯that, so much/many引⋯that 导。
⋯that 如此⋯以至于the scientist’srtrepowas so instructive that we were all very excited.科学家的报告很有启发性,我们感到很兴奋。
he always studied so hard that he made great progress.他总是那么努力,结果他取得了很大的进步。