从since when说起
It is +时间+since when before
It+be+时间+before/since/when/that句型辨析I since1. 翻译“It is/has been+时间段+since从句”(1)当从句谓语动词为非延续性动词时，表示这段时间从该动作开始时算起，即“自从做……以来已经多久了”。
(2)当从句谓语动词为延续性动词时，表示这段时间从动作结束时算起，即“自从不做……以来已经多久了”。
It is two years since he joined the army.他参军两年了。
(从参军那一刻算起)It is two years since he was a soldier.他退役两年了。
(从他不再是士兵算起)2. 时态主句为现在时（一般或完成），从句都是一般过去时。
主句为过去式（一般性都用was就够了），从句都是过去完成时II before1. 翻译It was/will be+时间段+before...过多长时间将发生某动作或事情；或过了多久发生了某事或动作。
It was three years before he finished the work.他花了三年才完成这项工作.It will be three years before he finishes the work.他得花三年才能完成这项工作. 2.It won't be/take long before...不久就会…It won't be long before he finishes the work.他不久就会完成这项工作.2. 时态主句为过去式（一般性都用was就够了），从句用过去时主句为将来时，从句用现在时（用一般现在时表示将来）III when1. 翻译It is + 时间点+ when…当发生什么的时候是什么时候…It was one o’clock when he came in .2. 时态主句是什么时态，从句就是什么时态3.常考与强调句的区别It was five o'clock when we arrived at the small mountain village.It was at five o'clock that we arrived at the small mountain village.强调句去掉it、be和that，余下的部分仍是一个完整的句子。
since when的用法
since when的用法引言“since when”是一个疑问句，常用于询问某事情发生的起始时间。
在英语中，这个短语通常用于质疑或询问某个事件或状态何时开始。
本文将详细探讨”since when”的用法，包括它的语法形式、常见的回答方式以及相关的注意事项。
语法形式“since when”的语法形式较简单，由两个部分组成：介词”since”和疑问副词”when”。
这两个词常常连在一起使用，表示对某个时间点或事件的起始时间进行疑问。
常见回答方式当被问到”since when”时，可以用多种方式来回答。
以下是常见的回答方式：1.具体时间回答：–Since 2010.（从2010年起）–Since last week.（从上周起）2.持续时间回答：–Since a month ago.（从一个月前起）–Since I was a child.（从我还是个孩子的时候起）3.事件回答：–Since I moved to this city.（从我搬到这个城市起）–Since I got a new job.（从我找到新工作起）注意事项在使用”since when”时，需要注意以下几点：1.适用范围：“since when”通常用于询问某事的起始时间，特别适用于询问较长时间段的事件，如从某年开始的习惯或从某个时间点开始的状态。
2.客观性：回答”since when”的问题时，需要提供客观真实的时间点或事件，并避免主观臆断或夸大事实。
3.回答的语气：回答”since when”时，可以使用简洁明了的语气，直接回答具体时间、持续时间或事件，以便清晰明了地表达起始时间。
4.答案的灵活性：回答”since when”的问题时，可以根据具体情况灵活选择回答的方式，如具体时间、持续时间或事件，以适应不同的语境和场合。
结论“since when”是一个常用的疑问句，用于询问某事情的起始时间。
通过介词”since”和疑问副词”when”的组合，可以清楚地表达对起始时间的疑问。
when,before,since-经典句子结构用法讲解(2018年1月21日)
(4) had not /hardly /sceracely…when… He had not/hardly/scarcely fallen asleep when the telephone rang. 他刚要入睡电话就响了。 (5) had just done …when … I had just gone to bed after a very hard day when the phone rang. 在劳累了一天之后我刚刚就寝，电话铃就响了。 (6)还可以表示原因“既然”，相当于since; considering that. It was foolish of you to take a taxi when you could easily walk there in five minutes .
6. (06天津) The cost of living in Glasgow is among the lowest in Britain, ______ the quality of life is probably one of the highest. A. since B. when C. as D. while D. 7. (04年江苏) ______ I accept that he is not perfect, I do actually like the person. A. A. While B. Since C. Before D. Unless 8.______ entered the office when he realized that he had forgotten his report. A. He hardly had B. Had he hardly C Hardly had he C. D. Hardly he had
英语时间状语从句的用法及有关说明
英语时间状语从句的用法及有关说明一、普通类从属连词引导时间状语从句的普通类从属连词有when（当……时），while（在……期间），as（当……，一边……一边……），before（在……之前），after（在……之后），since（从……以来），till/until （直到），whenever（无论何时），as soon as（一……就）等。
如：When I went into the classroom, he was reading. 当我走进教室时，他正在看书。
He read a newspaper as he went along. 他边走边看报纸。
We must strike while the iron is hot. 我们必须趁热打铁。
I will tell you after they leave. 于他们走后我再告诉你。
I told him to come back whenever he wants to.我告诉他什么时候想回来就回来。
I waited till/until she was back. 我一直等到她回来。
Once time is gone, you will never get it back. 时间一旦失去就再也得不到了Things were different when I was a child. 我小时候情况与现在不同。
We must strike while the iron is hot. 我们要趁热打铁。
It’s a long time since I met you last.从上次见到你，已有很长时间了。
He waited until she was about to leave. 他等着一直到她准备离开。
注意：在时间状语从句中，不能用一般将来时、过去将来时态或将来完成时，而要用相应的一般现在时态、一般过去时或现在完成时来代替。
如：I’ll telephone you as soon as I get there.我一到达那里就打电话给你。
when-before-since区别及用法
storm started.
AA.. wwhen
B. while C. until
D. before
2. (02上海) He was about to tell me the secret ______ someone
patted him on the shoulder.
A. as
B. until
C. while D. whheenn
when,before,since句型归纳
1、when 句型： (1) be doing sth…when…
He was still smiling when the door opened and his wife came in.
他正笑着的时候门突然开了，他妻子走了进来 。
(2) be about to do sth…when… We were about to start when it began to rain. 我们刚要出发，天就开始下雨了。
It is 5 years since he left Beijing . 他离开北京5年了
It has been 3 years since he came back from abroad.自从他回国已经三年了
3.since句型
It is/has been＋时间段＋since sb. did… §②§did动作为持续动词（延续性），翻译为 自从不做某事有多长时间
(4)hardly /sceracely…when… (一…就…) He had not/hardly/scarcely fallen asleep when the telephone rang. 他刚要入睡电话就响了。
We had scarcely arrived when he asked us to leave. 我们才刚刚到他就叫我们走了.
since when的用法
since when的用法Since when的用法“Since when”是一个常用的英语短语，通常用于询问某件事情或情况的开始时间。
它可以用来询问某人何时开始做某件事情，或者某个情况何时开始发生。
在口语中，这个短语经常被用来表达惊讶或不满。
例如，当你的朋友突然开始说流利的法语时，你可以问：“Since when do you speak French so well?” 这个问题的意思是你惊讶于他的法语水平，想知道他何时开始学习法语并变得如此流利。
“Since when”也可以用来表达不满。
例如，当你的朋友开始对你的生活方式提出批评时，你可以问：“Since when do you care about how I live my life?” 这个问题的意思是你不满于他的批评，想知道他何时开始关心你的生活方式。
除了口语中的用法，"since when"也可以用于书面语中。
例如，在一篇文章中，你可以写道：“Since when did the government startto prioritize environmental protection?” 这个问题的意思是你想知道政府何时开始将环境保护作为优先事项。
总之，“since when”是一个非常有用的英语短语，可以用于询问某件事情或情况的开始时间，也可以用于表达惊讶或不满。
在口语和书面语中都可以使用。
总结：1. “Since when”是一个常用的英语短语，通常用于询问某件事情或情况的开始时间。
2. 它可以用来询问某人何时开始做某件事情，或者某个情况何时开始发生。
3. 在口语中，这个短语经常被用来表达惊讶或不满。
4. “Since when”也可以用于书面语中。
5. 总之，“since when”是一个非常有用的英语短语，可以用于询问某件事情或情况的开始时间，也可以用于表达惊讶或不满。
Since when的语义和用法
Since when的语义和用法作者：张满胜来源：《新东方英语》2014年第04期与when经常搭配使用的介词是since，两者构成since when的搭配组合。
Since when既可以引导定语从句，也可以引导特殊疑问句。
下面笔者来谈谈since when引导不同句子类型时的语义与用法。
Since when引导定语从句我们先来看下面这道选择题。
1. The book was written in 1946， ____ the education system has witnessed great changes.A. whenB. during whichC. since thenD. since when本题的正确答案是选项D，填入后得到这样一个句子：“The book was written in 1946，since when the education system has witnessed great changes.”（那本书写于1946年，从那以来教育体制发生了很大变化。
）我们知道，since表示时间，意为“自从……以来”，常与完成时态搭配使用，尤其是现在完成时态（have done）。
同理，当since when引导定语从句时，从句谓语也要用现在完成时态，如本句中就使用了has witnessed。
现在我们分析一下其他三个选项错误的原因。
选项A：如果选择选项A的when，那么when指的是in 1946，此时句意就变成了教育体制的改变只是发生在1946年，此时定语从句应该用一般过去时态witnessed。
由此可见，when 与定语从句中的现在完成时态has witnessed有时间冲突，故选项A是错误的。
选项B：如果选择选项B的during which，那么during which可以理解成during the year of 1946，此时定语从句也要用一般过去时态。
选项C：选项C的since then不是连词，不能引导从句。
时间状语从句的用法及常见错误
时间状语从句的用法及常见错误时间状语从句，是英语中的重要语言结构之一，相信很多学习英语的同学们都有接触过。
它的作用是在主句中描述时间，常常是表达事件发生的先后顺序。
然而，由于语法结构的复杂性以及细节的繁琐，使得许多学习者在真正应用时出现了一些常见的错误。
本文旨在介绍时间状语从句的用法及常见错误，帮助读者加深对此语法结构的理解，更好地运用它。
一、时间状语从句的用法时间状语从句指的是在主句中用来描述时间顺序或时间点的句子，通常由连词when、while、as、before、after、since、until等引导。
例如：- When I arrived at the station, the train had already left.- While I was walking in the park, I met an old friend.- After I finish my homework, I will go to bed.时间状语从句也可以放在句首、句中、句末等不同位置，需要根据语境进行灵活运用。
例如：- When I was young, I used to play football every day.- I met an old friend while I was walking in the park.- I will go to bed after I finish my homework.此外，时间状语从句与各种时态、语态和情态动词搭配使用。
具体来说：1. 在一般现在时中，时间状语从句中通常使用一般过去时来表示过去的时间点或延续时间：- I always watch TV when I have free time.- He speaks Chinese fluently as he has been learning it for many years.2. 在一般过去时中，时间状语从句中通常使用过去完成时来表示更早的过去时间点或动作的完成：- After she had finished her homework, she went to bed.- When I arrived at the airport, the plane had already taken off.3. 在一般将来时中，时间状语从句中通常使用一般现在时或一般将来时来表示将来的时间点或延续时间：- I will call you as soon as I arrive in Shanghai.- She will be very happy when she sees the gift.4. 在现在完成时中，时间状语从句中通常使用过去时间来表示已经完成的动作：- She has visited many countries since she graduated from university.- I haven’t seen him since we went to school.5. 在情态动词中，时间状语从句中通常使用过去完成时来表示动作的完成：- He should have arrived by now.- I would have finished the task if I had more time.二、时间状语从句的常见错误尽管时间状语从句的知识点看似简单，但在实际应用中却存在一些常见错误。
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从since when说起，浅谈几个特殊的定语从句
定语从句是高考的热点之一，在每年的高考英语试题中，几乎所以省份都会考查一处定语从句。
而且，最近几年还考到了比较特殊的用法。
请看两道山东卷中的试题：
【典型例题】
1. He was educated at a local grammar school, ______ he went on to Cambridge. (2005年山东卷)
A. from which
B. after that
C. after which
D. from this
2. The book was written in 1946, ______ the education system has witnessed great changes. (2007年山东卷)
A. when
B. during which
C. since then
D. since when
【典例分析】
1. 句意：他在当地一所文法学校上学，之后他便去了剑桥。
根据句意可排除A、D两项；after that意为“然后，之后”，但不能引导一个定语从句，因此B项也被排除；after which 相当于and after that，不但符合语境，而且能引导定语从句，故答案为C。
2. 句意：该书写于1946年，从那以后教育制度已经历了巨大变化。
根据从句中的现在完成时态和句意，我们可排除A、B两项；短语since then意为“从那以后”，但不能引导一个定语从句，因此也排除了C项；故此处应选D项，since when相当于and since then，它能引导一个定语从句。
【同类例句】
除了上述例题外，我们还回见到下面的例子：
1. At home, he never seems to have time until after 10:30 pm, by which time his children have gone to bed.
= At home, he never seems to have time until after 10:30 pm, and by that time his children have gone to bed.
在家里，他好像十点半之后才有空，到那时孩子们已上床睡觉了。
2. We were next-door neighbors for three years, during which time we met only twice.
= We were next-door neighbors for three years, and during this/that time we met only twice.
我们做了三年隔壁邻居，在此期间我们只见过两次面。
3. It occurred to him that it would save a lot of trouble to destroy the advertisement, in which case, he would have to explain to Peter.
=It occurred to him that it would save a lot of trouble to destroy the advertisement, but in that case, he would have to explain to Peter.
他曾想到过，撤销广告会避免很多麻烦；但是如果那样的话，他必须向皮特做出解释。
4. I was told my work was unsatisfactory, at which point I submitted my resignation.
= I was told my work was unsatisfactory, and at this/that point I submitted my resignation.
被告知我的工作不能令人满意，闻讯后我便递交了辞呈。
5. He is studying economics, which knowledge is pretty important today.
= He is studying economics, and this knowledge is pretty important today.
他在学习经济学，这门知识在当今非常重要。
6. He stood by the window, from where he could see what was happening outside.
= He stood by the window, and from there he could see what was happening outside.
他站在窗子旁边，从那儿他能看到外面发生的一切。
【小结点拨】
根据上面的例句，我们不妨做出如下总结：①带有this, that的短语，引导定语从句时，要将this, that变为which；②带有here, there的短语，引导定语从句时，要将here, there变为where；③带有then, now的短语，引导定语从句时，要将then, now变为when；④带有one's的短语，引导定语从句时，要将one's变为whose。
【自我小测】
1. He believes in public ownership, ______ idea I quite opposed to.
A. this
B. that
C. which
D. what
2. The baby is due in May, ______ the new house should be finished.(2010年泰安二轮质检)
A. by then
B. by which
C. by when
D. since when
3. Mark was a student at this university from 1999 to 2003, ______ he studied very hard and was made Chairman of the Students’ Union. (2005年重庆)
A. during which time
B. for which time
C. during whose time
D. by that time
4. This is the small house less than 15 square meters, under ______ roof lives a large family of three generations. (2008杭州高三模拟)
A. which
B. that
C. its
D. whose
5. The famous scientist, ______ a dinner party will be held tonight, is to arrive soon. (2008山东济南)
A. in honour of him
B. in his honour
C. in whose honour
D. in which honour
【答案】1. C 2. C 3. A 4. D 5. C。