关于since的从句用法
知识点：It be +一段时间+since ..... 当主句中的be为is/hasbeen时，since从句中用一般过去时当主句中的be为was时，since从句中用过去完成时 问题：1 主句中的be只能是单数is、has been/was这些形式的固定搭配吗？2 这个固定搭配是否遵循since引导从句中的语法规则（知识点：since引导的从句中动词为非延续动词，表示“自从.....多久了”。since引导的从句动词为非延续动词，表示“从该动作结束以来已经多久了”）3 我在语法书上看到这样一个例子A It was years since the war broke out . B It was half a year before they marrid.是否有错？（因为这种主从关系的句子主句时态往后推一个就是从句时态）
since的用法：译作“自从…以来”
1、接时间点：如 I have stayed in that country since 1995. 要求：谓v.用现在完成时，而且须是延续性动词。
2、接一段时间 + ago：如 They have lived in that house since two years ago. 要求：谓v.用现在完成时，而且须是延续性动词。
3、接时间状语从句：如 I have loved her since I met her last time. / Lily has stayed at home since she left school. 要求：主句的谓v.用现在完成时，而且须是延续性动词；从句的谓v.用一般过去时，而且须是终止性动词。
4、用于句型“It’s / It has been + 一段时间 + since + 时间状语从句”中，译作“自从…以来, 已经…(时间)了”。如 It’s / has been three months since he moved to this city. 要求：主句的谓v.用一般现在时或现在完成时；从句的谓v.用一般过去时，而且须是终止性动词。
5、用于句型“一段时间 + has passed since + 时间状语从句”中，译作“自从…以来, …
(时间)已经过去了”。如上个例句还可写成：Three months has passed since he moved to this city. 要求：主句的谓v.用现在完成时，而且动词必须是has passed；从句的谓v.用一般过去时，而且须是终止性动词。
扩展资料
since用作介词的意思是“从…以来,自从…之后”,其宾语常指过去的一个时间点,其含意通常指持续到说话时刻的动作或情况开始于什么时候。
since之后常接名词、动名词作其宾语, since then意为“从那以后”。
since用作副词表示“以前”时还可和long, ever连用。long since意为“好久以前”, not long since意为“就在不久前”, ever since意为“从那时起,此后一直”。
since用作连词作“自从…以来〔以后或,现在〕”解时,引导时间状语从句,在主句是现在完成时的情况下,如果since从句中谓语动词用一般过去时,则表示动作或状态的完成,计时的起点是动作或状态完成的那一时刻,在语意上,非延续性动词的句子与其词意一致,含有肯定的意味,而延续性动词的句子与其词意恰好相反,含有否定的意味。
(1)接时间点：如 I have stayed in that country since 1995. 要求：谓v.用现在完成时，而且须是延续性动词。
(2)接一段时间 + ago：如 They have lived in that house since two years ago. 要求：谓v.用现在完成时，而且须是延续性动词。
(3)接时间状语从句：如 I have loved her since I met her last time. / Lily has stayed at home since she left school. 要求：主句的谓v.用现在完成时，而且须是延续性动词；从句的谓v.用一般过去时，而且须是终止性动词。
(4)用于句型“It’s / It has been + 一段时间 + since + 时间状语从句”中，译作“自从…以来, 已经…(时间)了”。如 It’s / has been three months since he moved to this city. 要求：主句的谓v.用一般现在时或现在完成时；从句的谓v.用一般过去时，而且须是终止性动词。
(5)用于句型“一段时间 + has passed since + 时间状语从句”中，译作“自从…以来, …
(时间)已经过去了”。如上个例句还可写成：Three months has passed since he moved to this city. 要求：主句的谓v.用现在完成时，而且动词必须是has passed；从句的谓v.用一般过去时，而且须是终止性动词。
(6)注：当since用于否定句时，主句的谓v.可以是终止性动词。如 He hasn’t seen the film since last month.
(7)相关词组：“从那时起”：ever since、since then、from then on.
注：ever since作为一个词组，放句尾可单独使用。如I have given up smoking ever since. 另外，还可在since后接句子。since前加ever，只是加重语气而已。如 I have given up smoking ever since I caught a bad cough.
(8) since还可引导原因状语从句，译作“由于；因为”，相当于because。如 Since he was lazy, he didn’t finish his homework.本回答被提问者采纳
(1)接时间点：如 I have stayed in that country since 1995.要求：谓v.用现在完成时,而且须是延续性动词.
(2)接一段时间 + ago：如 They have lived in that house since two years ago.要求：谓v.用现在完成时,而且须是延续性动词.
(3)接时间状语从句：如 I have loved her since I met her last time./ Lily has stayed at home since she left school.要求：主句的谓v.用现在完成时,而且须是延续性动词；从句的谓v.用一般过去时,而且须是终止性动词.
(4)用于句型“It’s / It has been + 一段时间 + since + 时间状语从句”中,译作“自从…以来,已经…(时间)了”.如 It’s / has been three months since he moved to this city.要求：主句的谓v.用一般现在时或现在完成时；从句的谓v.用一般过去时,而且须是终止性动词.
(5)用于句型“一段时间 + has passed since + 时间状语从句”中,译作“自从…以来,…
(时间)已经过去了”.如上个例句还可写成：Three months has passed since he moved to this city.要求：主句的谓v.用现在完成时,而且动词必须是has passed；从句的谓v.用一般过去时,而且须是终止性动词.
(6)注：当since用于否定句时,主句的谓v.可以是终止性动词.如 He hasn’t seen the film since last month.
(7)相关词组：“从那时起”：ever since、since then、from then on.
注：ever since作为一个词组,放句尾可单独使用.如I have given up smoking ever since.另外,还可在since后接句子.since前加ever,只是加重语气而已.如 I have given up smoking ever since I caught a bad cough.
(8) since还可引导原因状语从句,译作“由于；因为”,相当于because.如 Since he was lazy,he didn’t finish his homework.
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二、 一般过去时
4、 用于since引导时间状语从句中的谓语动词
1） 短暂动词的一般过去时,表示非持续性动作的结束.如：
The area has changed a great deal since I left. 自从我离开以来那地区发生了很大的变化.
It had been two years since he was in the army. 他参军两年了.
2） 持续性动词或状态动词的一般过去时,表示动作或状态的完成或结束.如：
It is / has been two years since he was in the army. 他复员两年了.
My classmates have written to me since I lived in the city. 我离开那个城市以来同学常常给我写信.