since 用法

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  • since的用法

    一、 用作介词,意思是“从……以来,自从”,常与完成时连用.

    I haven’t written home since Christmas.

    自圣诞节以来,我未曾写信回家.

    二、 用作副词,意思是“从那时以后(一直到现在)”,“其后(到现在之间)”; ever since从那以后一直 (更加强调since的用法).

    Things have not changed very much since.

    从那时起,情况并没有太大的改变.

    His first book was a great success and he has been famous as a writer ever since.

    他的第一本书非常畅销,从那时起他就成了一位名作家.

    He got a job with the firm in 1970 and has worked there ever since.

    他从1970年开始在那家公司任职,之后就一直在那里工作.

    三、 用作连词

    1.引导原因状语从句,相当于now that,意思是“因为……,既然……,鉴于……”.

    Since the rain has stopped,let’s go for a walk.

    既然雨停了,我们出去散散步吧.

    Since we are young,we shouldn’t be too afraid of making mistakes.

    因为我们还年轻,所以不应该太害怕犯错误.

    注意:since表示原因时,语气比because弱,表示的原因是对方已知的,或是句中不很重要的部分,是附带的原因,因此引导的从句不是信息的焦点,不能回答why的提问,也不能用在强调句型中作为被强调的内容.since引导的从句往往放在主句之前.

    2.引导时间状语从句,此用法较复杂.

    (1) 若since引导的状语从句的谓语动词是终止性动词(如go,come,leave,start,begin等)的过去时,则从句表示的时间是“从该动作开始的那一时刻起”.这是最常见的一种用法.如:

    He has studied very hard since he came to our school.

    自从来到我们学校,他学习就非常努力.

    Great changes have taken place in our school since you left.

    自从你离开这里,我们学校发生了很大的变化.

    (2) 若since引导的状语从句的谓语动词是持续性动词或表示状态的静态动词(如live,stay,study,learn,smoke,be等)的过去时,则从句表示的时间是“从该动作或状态的完成或结束时算起”.如:

    I haven’t heard from him since he lived here.

    这句话应译为:从他不住这儿起,我一直没有收到他的信.

    I haven’t eaten snakes since I was a student at school.

    was表示状态,因此该句可理解为:I haven’t eaten snakes since I left school.

    自从我毕业后就一直没吃过蛇.

    试比较:

    He has written to me frequently since I was ill.

    自从我病愈以来,他经常给我写信.(从句谓语为状态动词)

    He has written to me frequently since I fell ill.

    自从我生病以来,他经常给我写信.(从句谓语为终止性动词)

    (3) 若since引导的状语从句的谓语为持续性动词或静态动词的现在完成时,则表示动作和状态延续到现在(说话时刻),其表示的时间的起点应从动作发生之时算起.如:

    He has written to me frequently since I have been ill.

    这里have been ill表示状态的持续性,时间的起点应从:“开始生病”时算起.因此此句可理解为:“自从我生病以来,他经常给我写信.”

    试比较:

    I’ve written her 20 letters since I have been here.

    自从我来到这,我已经给她写了20封信.(从开始算起)

    I’ve written her 20 letters since I was here.

    自从我离开这儿,我已经给她写了20封信.(从结束算起)

    (4) It is + 段时间 + since.../ It has been + 段时间 + since...表示“从……起已有多长时间了”.两句型意思相同,前者是规范说法,后者是口语说法.

    用法:since从句中常用一般过去时,若从句中是持续性动词的一般过去时,则表示该动作结束有多长时间了.如:

    It is three years since he smoked.

    他不吸烟已有3年了.

    试比较:

    It is three years since he began to smoke.

    It is three years since he has smoked.两句均意为:他吸烟已有3年了.

    注意:在这种结构中,since引导的从句绝对不能用否定式的谓语动词来表示否定意义,试比较:

    他好久没学汉语了.

    误:It is a long time since be didn’t study Chinese.

    正:It’s a long time since he studied Chinese.

    (studied为持续性动词,应从其动作结束时算起)