Since\before\until的辨析
练习：the soldier devoted most of his time to the security of the country. and it has been three years ____he went home .A. before B. after C. since D until
,It has been two years___ I graduated from my high school.
自从我高中毕业,已经两年了.
It is still a year ___ I graduate from my college.
在我大学毕业之前,仍然还有一年的时间.
I had finished my homework ____ it was 9 o`clock last night. 在昨天晚上9点之前,我就已经完成了我的作业.
I did not finish drawing the picture ____ it was 9 o`clock last night. 直到昨天晚上9点我才画完这幅画.
since是自从的意思”一段时间+since”表示从这个时间开始到现在---自从~以来. 用法上It + ( 现在完成时) + 一段时间+ since + ( 一般过去时)例句：It is / has been four days since I caught a cold.我感冒已四天了It is / has been two weeks since we met last.自从我们上次见面以来已过了两周.
一段时间+ before表示在这个时间之前,或者大约在这个时间上就会发生某事.用法上It + ( 一般将来时) + 一段时间+ before +( 一般现在时)例句：It will be five years before he meets you again. 五年之后他就会再见你的. It + be (not) + long before表示"(不)很久/ 才…"或"(没)过多久就/ …"It was (not) long before ….(谈论过去)\ It will
(not) be long before ….(谈论将来)\ It was long before she came back.\没过多久她就回来了.\ It will be long before we meet again.\x0d很久以后我们才会再见面.\ It will not be long before we turn our hope into reality. 过不了多久我们的希望就会变成现实. 这里it指时间, before是连词,引导时间状语从句.long可用一段时间来替代.
Until
1. 如果（主）句中的谓语动词是终止性动词即非延续性动词,应采用
“...not ...until ...”结构,意为“……到……时候才……”.例如：
You mustn’t eat anything until you see the doctor.
看过医生之后,你才能吃东西.
Don’t get off the bus until it has stopped. 车停稳了以后再下车.
2. 用于肯定句中：
1) It may last until Friday.这可能要延续到星期五.
2) He will be working until 5 o'clock.他将一直工作到五点钟.
3) She was a bank clerk until the war, when she trained as a
nurse.她战前是个银行职员,战时受训当了护士.
不难看出until 用于肯定句中,表示句子的动作一直持续到until短语所表示的时间为止,即表示动作的终点.一般可译为“直到……时(为止)”或“在……以前”.在这种用法中,句子的谓语动词必须是持续动词(非瞬间动词),如live, wait ,last, love, like, stay, work, continue等.
3. 如果谓语动词为否定式,则until应译为“到……时候才”,即“在……
以前不”.例如：
I did not watch TV until she came back.（= I began to watch TV
when/after she came back.）
直到她回来我才开始看电视.
4. 连词until引导的从句中谓语动词的时态.
1）主句的谓语动词为一般现在时或一般将来时时,until从句中的谓语动词为现在完成时,用来强调从句谓语动词表示的动作发生在主句谓语动词表示的动作之前.试比较：
I won’t go to bed until I have finis hed my homework.
我要完成作业才睡觉.
2）主句中的谓语动词为一般过去时时,从句中的谓语动词为过去完成时,用来强调从句谓语动词的动作发生在主句谓语动词表示的动作之前.试比较：
Li Lei didn’t come until the film had begun.
直到电影开演,李雷才来.
〔特别提醒〕till和until的意思基本相同,用法也基本一样,但until 语气较重,多用于较正式的文体里.till多用于英式英语,until多用于美式英语；till不能用在句首,也不能用在not开头的短语或从句里,而until可以.例如：
Until he came home, we knew the news.
在他到家之前,我们不知道这消息.
Not until nine o’clock yesterday evening did we finish the work. until和before用法的区别
一、在下列情况下,两者可互换用,但含义略有不同.before表示“在……之前”的意思,强调时间先后关系；而until表示“直到……才”的意思,主句是肯定句则表示主句动作的终止时间；主句是否定句则强调主句动作的起始时间.
1.主句为否定式终止性谓语动词.常见的动词是open, start, leave, arrive, finish, stop等.例如：
(1)The noise of the street didn't stop until/before it was midnight.
(2)The children won't come back until/before it is dark.
(3)I didn't leave the lovely boy until/before his mother came home.
2.主句为肯定式、延续性谓语词,这类动词用stand, stay, talk ,be, wait 等.例如：
(1)He lived with his parents until/before he graduated from school.
(2)I will wait until/before he comes to my help.
(3)I shall stay here until/before you come back.
二、在下列情况下,用before不用until.
1.主句这肯定式、终止性谓语动词,只用before.“在…之前就”、“没来的及就”
(1)He fell asleep before I could take off his clothes.
(2)We arrived there before it started to rain.
(3)The holiday came to the end before I knew it.
(4)He almost knocked me down before he saw me.
2.主句谓语动词强调动词的迟缓性,只用before,常伴有时间段状语或时间段暗示.例：
(1)It was quite some time before he found the elephant at all.
(2)We had walked a long way before we found some water.
(3)We had sailed for two days before we saw the land.
(4)The fire lasted about four hours before the firefighters could control it.
(5)It was midnight before my brother came home.
(6)It was three months before they met again.
3.如果强调从句谓语动作未发生,就发生主句谓语动作,只用before.常译为“未及”,“不”或“不等……就”.例：
(1)We can leave early in the morning before it gets too hot.
(2)I must write it down before I forget it.
(3)We do want to buy something now before prices go up.
4.在某些特定句型中用before.例如：
(1)It was not long before the whole country rose up.
(2)It will probably not be long before they understand each other.
三、下列情况一般区别用until.
1.主句是持续性谓语动词时,肯定、否定都可以,但意义完全不同.肯定表动作终止,而否定表动作开始.例如：
(1)We discussed the problem until/before he came back.我们一直
讨论到他回
来.
(2)We didn't discuss the problem until he came back.我们一直等到他回来后才讨论问题.
2.not…until句型尽管在某些情况下可与before互换用,但在强调句中一般仍用until.
例如：
(1)It was not until he told me that I knew it.
(2)It was not until he finished his homework that he went home.
五大基本句型 一、及物动词和不及物动词 1.及物动词（vt.）：不能单独使用。必须接宾语。 2.不及物动词（vi.）：可以单独使用。但如果要接宾语或补语，必须要介词连接。 注意：1.很多词既可以是及物动词也可以是不及物动词。 2.一般情况下，来往型动词（go ,come, arrive, move等）、存在型动词（be、exist）、 发生型动词（happen等）都是不及物动词 3.特别注意marry（和……结婚），reach（到达……），enter（进入……），attend（参 加……），discuss（讨论……）这些词都是及物动词 二、句子主要成分 1.主语：句子主要陈述对象，也是动作的发出者。由名词（代词）担任。 2.谓语：主语发出的动作。只能由动词担任。 3.宾语：动作的承受着。由名词（代词）担任。 4.补语：起补充说明的作用。可以由名（代）形担任 注意：1.主谓必须放在句子最前面。谓语必须紧跟在主语后面。 2.谓语动词的类型，决定了句子的类型。 三、五大类型 类型一 主+谓（S+V） 例：I go._________________________________________________________________ We study.____________________________________________________________ My mom cooks.________________________________________________________ 这些句子中的动词都是_______动词。 这些句子的形式都过于简单，因此我们会在后面添加上_____词，让它们更完整。 但是________词并不是句子的基本要素，是可有可无的。 类型二 主+谓+宾（S+V+O） 例：I read this_______.(书) You want ________.(快乐) I love ________. (你) 这种句型使用的频率最_____。 这里的动词全是_______动词，即动词的后面必须要跟上_____语。且宾语要由______ 词来担任 类型三 主+系+表（S+L+P） 例：I am._________________________________________________________________ She looks._____________________________________________________________
before和ago都能表示在一段时间以前，但是二者的内涵和具体用法有明显的区别： 1. before表示从过去或将来某一时间算起多少时间以前，由于与这一时间状语连用的行为先发生在过去或将来某一时刻之前，因此往往出现在过去完成时态或将来完成时态中。例如： ①I called him up last night，but his mother told me he had left for Wuhan two days before. ②She said that she had married him five years before. 2.如果不具体表明多少时间以前，before意为"从前；以前"，表示从现在开始追溯到过去一段时间，或者主句的谓语动词表示的是经常、反复发生的行为，以副词的形式置于句末，可以用在现在完成时态中。例如： ①I have never been to Beijing before. ②Have you ever seen a tiger before? ③I often go over the lessons that I have learned a few days before. 注意：before前的时间状语如果是特定的，含义不一样。试比较： He said he had arrived here a day before. (一天前) He said he had arrived here the day before. (前一天) 3. ago指的是从现在起到过去时间的某一点的一段时间。这个时间状语常与一般过去时态或过去进行时态连用。例如： ①I graduated from the college twenty years ago. ②I was asked what I was doing a month ago. 4. 表示在某一时间点或事件以前时，只能用before，不用ago。因为这种用法是将before当作介词或连词使用。ago不具有这种功能。例如： ①He will come back before eleven o'clock.
英语句型转换
英语句型转换 一、将下列句子改为否定句。 1、He takes some pictures every day.他每天拍一些照片 He doesn't take photos every day。他每天都不拍照片 2、It’s cheap enough.够便宜的了 It's not cheap这一点不便宜的 3、She gave her brother some tapes about folk music.她给她哥哥对民间音乐磁带 She didn't give her brother a tape of folk music.她没给她哥哥民间音乐磁带 4.This is the first time we come to Australia. 这是我们第一次来澳大利亚 This is not the first time we come to Australia.这不是我们第一次来澳大利亚 5、There are a lot of lovely animals there.那儿有许多可爱的动物 There are no lovely animals there。那儿没有可爱的动物。 6、My mother will take me to Beijing for my holiday next Sunday.我妈妈要带我去北京，下星期日我的假期 My mother doesn't take me to Beijing. I won't have a holiday next Sunday。我妈妈不带我去北京，下星期日我没有假期。 7、You can find many tall trees in the picture of the park.你可以在公园的照片发现有许多高大的树木. You don't find many tall trees in the Park Photos你在公园的照片没有发现有许多高大的树木 8、I am listening to music.我在听音乐 I didn't listen to music。我没有听音乐 9、Mike is a student.迈克是个学生
十大词性、句子成分分析、五大基本句型及句子类型讲解与练习 一、新课导入 个体名词 厂 「 集体名词」可数名词 普通名词 物质名词 1. 名词 抽象名词」*，不可数名词 专有名词 功能：表示人或事物的名称 人称代词： 主格 宾格（注意it 的用法） 物主代词：形容词性物主代词 名词性物主代词 指示代词：this, that, these, those 单数： myself, yourself, himself, herself, itself, on eself 反身代词： 复数：ourselves, yourselves, themselves 2?代词 疑问代词： who, whom, whose, what, which. 简单不定代词： One/on es, Either/ neither, both/all, each/ every ano ther, other, the other, others, the others 复合不定代词： somebody, an ybody, n obody 不定代词、 some one, anyone, no one somethi ng, any thi ng, nothing everybody, every one, everyth ing 功能：用来代替名词、形容词或数词等 基数词 序数词 功能：表数量或顺序 定冠词 不定冠词 零冠词 //功能：用在名词前，帮助说明名词所指的人或事物 表地点： at/ in/ on/ to, above/ over/ on, below/ under/ undern eath 表时间： in/ on/ at, in/ after, from/since from, after/ beh ind, 表运动： across/ through/ over/ pass … 表方位：…. 其他 3. 数词: 4. 冠词: 5.介词:
1. It is +一段时间+ since从句 在“It is +时间段+ since从句” 句型中，如果since从句的谓语动词是瞬间性动词，表示肯定意义；如果since从句的谓语动词是延续性动词，则表示否定意义。例如： 1) It is / has been ten years since he left Beijing. 译文：自从他离开北京已经十年了。分析：since从句中的left是leave的过去式，是瞬间性动词，表示肯定的意思，left译为“离开” 2) It is / has been ten years since he was a doctor. 他不当医生已经十年了。 分析：since从句中的系表结构表示一种状态，这种状态是延续性的，表示否定意义，译为“不是，不当” 注：时间的计算一律从since从句的动作完成或状态结束时算起。 2. It was / will be +一段时间+
before从句 1) 在“It was + 一段时间+ before从句” 句型中，若主句是一般过去式，从句也是一般过去式时： ①若主句是肯定句，翻译成“过了多长时间之后才……”例： It was long before they found their son. 过了很久他们才找到他们的儿子。 ②若主句是否定形式，翻译成“没过多久就……” 例：It was not long before the couple met again. 没过多久这对夫妻就见面了。 2) 在“It will be + 一段时间+ before 从句”句型中，若主句是一般将来时，从句也是一般现在时： ①若主句是肯定句，翻译成“要过多长时间之后才……” 例：It will be half a year before I come back. 半年后，我才回来。 ②若主句是否定形式，翻译成“用不了多久就……” 例：It won’t be long before we meet
初中英语学习材料 madeofjingetieji since 和for 的用法(用于现在完成时) 表示过去已经开始持续到现在的动作或状态常用的时间状语有：for, since, how long, so far, these days等。 1. since : a).since +时间点①年代②时刻数③一段时间+ago b).现在完成时：主句(主语+have/has +延续性动词的过去分词)+ since +从句一般过去时 c) It’s +时间段+since +短暂性动词的过去式 d).时间段+has passed +since +短暂性动词的过去式 for +一段时间 练习： 用since和for填空 1) ______ two years 2) _______ two years ago 3) _______ last month 4) ______ 1999 5) _______ yesterday 6) _______ 4 o’clock 7) ______ 4 hours 8) _______ an hour ago 9) _______ we were children 10) _____ lunch time 11) ______ she left here 12). He has lived in Nanjing ________ the year before last. 13). I’ve known him __________ we were children. 14). Our teacher has studied Japanese _________ three years. 15). She has been away from the city ___________ about ten years. 16). It’s about ten years __________ she left the city. 2. for: for +一段时间= since +一段时间+ ago 3. 与时间段连用时，短暂性动词应改为相应的延续性动词。 1) come/go to ------ be at /in 2)leave ----be away from 3)buy ----have 4) borrow /lend -----keep 4)open ---be open 5)close---be closed 6) die---be dead 7) start/begin ----be on 8) join—--be in /be a member of /be a soldier 9) become –be 10) fall asleep ---be asleep 11)catch a cold – have a cold 12) have/has gone to → have been in 13) put on → wear14) finish/end → be over 15) marry → be married 练习：.短暂性转换延续性 1) His grandfather died two years ago . His grandfather has ____ ____ for two years. _____two years _____ his grandfather ____. Two years ____ ____ ____ his grandfather _____. 2) I became a teacher in 2000. I ________ __________ a teacher for _________ _________. 3) The shop closed two hours ago. The shop ________ _________ _________ for _________ _________. 4) The door opened at six in the morning. The door ________ ________ ________ for six hours. 5)He left Fuzhou just now. He _______ ________ ________ _________ Fuzhou for five minutes. 6)The film began two minutes ago. The film ____ ____ ____ for ____ ____.How time flies! 7)They borrowed it last week. They _________ _________ it since __________ __________. 8)I bought a pen two hours ago. I _________ _________ a pen for ________ __________. 9)They married in 1990. They ________ _________ __________since _________. 10)The meeting finished at six. The meeting ________ ______ ______ for six hours. 11)My brother joined the army two years ago.
1、在be动词后加not。如：is not ，are not ，am not 2、在can，should，will等后加not。 如：cannot，should not，will not； 3、上述都没有的，在动词前加助动词否定形式don’t/doesn’t/didn’t。 4、some 改成any。 如：I am a girl. →I am not a girl. You are a student. →You are not a student. →You aren’t a student. This is Tom’s bag, →This is not Tom’s bag. →This isn’t Tom’s bag. 1、把be动词放在句首，剩下的照抄，（some 改成any，I改成you，my改成 your，）句点改成问号。 2、把can，shall， will等放到句首，剩下的照抄，（some 改成any，I改成 you，my改成your，）句点改成问号。 3、上述都没有的，在句首请助动词Do/Does/Did帮忙，剩下的照抄，（some 改 成any，I改成you，my改成your，）句点改成问号。 注意：句首的第一个字母要大写，句尾标点应为“？”。 如： I am in Class 6. →Are you in Class 6 You are from America. →Are you from America It is an orange. →Is it an orange 4、就一般疑问句回答 一般疑问句有两种回答，即：肯定回答和否定回答。其中，肯定回答用yes,否定回答用no。语句顺序为：Yes + 主语 + am /is/ are/was/were.|can.|do/does/did|; No + 主语+ am not/ isn’t/ aren’t 如：—Are you an English teacher→Yes, I am. /No, I am not. —Is that a bird →Yes, it is./ No, it isn’t. “就划线部分提问”是小学阶段英语学习的难点，但是一旦掌握了规律，就变得容易多了。小学英语对划线部分提问之答题口诀： 一代：用正确的疑问词代替划线部分。 二移：把疑问词移至句首 三倒：颠倒主谓语，但对主语或其定语提问时除外（some 改成any，I改成you，my改成your）， 四抄：照抄句子剩余部分。 ★特殊疑问词的确定要根据划线内容而定,在小学阶段常出现的有以下几种： 1.划线部分是“事或物”，特殊疑问词用what 如: This is a book.---What is this I often play football on Saturdays .---What do you often do on Saturdays 2.划线部分是“人”，特殊疑问词用who 如:He is my brother. ---Who is he ３、划线部分是“地点”，特殊疑问词用where 如:The box is on the desk.---Where is the box ４、划线部分是“时间”，特殊疑问词用what time或when 如:It's seven twenty . ---What time is it
英语简单句5种基本基本句型 简单句的基本形式是由一个主语加一个谓语构成。其它各种句子形式都是由此句型发展而来。 一、句型1: Subject (主语)+ Verb (谓语) 这种句型中的动词大多是不及物动词，所谓不及物动词，就是这种动词后不可以直接接宾语。常见的动词女口：work, sing, swim, fish, jump, arrive, come, die, disappear, cry, happen 等。 eg The birds are f lying 那些鸟在飞。 Things change事物是变化的。 Nobody went没有人去。 练习：汉译英 1) Li Ming works very hard. 李明学习很努力。 2) The sun was rising. 3) Spring is coming. 4) I'll try. 5) We all breathe, eat, and drink. 6) Did you sleep well last night ? 7) The book sells well. 8) The engine broke down. 9) The accident happened yesterday afternoon. 事故是昨天下午发生的。 10) We have lived in the city for ten years. 11) Lucy and Mary get up early every morning. 12) Xiao Li went to bed as soon as he came home. 小李回家后,立刻就睡觉了。 13) I'll go when I have had my dinner. 我吃了饭就去。 14) What he said does not matter. 15) They had talked for half an hour when I came in. 16) His parents have worked in the factory for more than ten years. 17) So they had to travel by air or boat . 18) We got up early so as to catch the first bus . 19) She sat there alone , reading a novel . 20) He came back when we were eating . 21) Weak buildings will fall down in an earthquake. 二、句型2: Subject (主语)+ Link. V(系动词)+ Predicate(表语) 这种句型主要用来表示主语的特点、身份等。其系动词一般可分为下列两类： (1) 表示状态。这样的词有：be, look, seem, smell, taste, sound, keep 等。如： 1) This kind of food tastes delicious. 这种食物吃起来很可口。 2) He looked worried just now. 刚才他看上去有些焦急。 (2) 表示变化。这类系动词有：become, turn, get, grow, go 等。如： 1) Spring comes. It is getting warmer and warmer. 春天至U了，天气变得越来越暖和。 2) The tree has grown much taller than before. 这棵树比以前长得高多了。 练习：汉译英 1) The dinner smells good. 2) Everything looks different. 3) He fell asleep. 4) This is an English-Chinese dictionary.
after，before，since用法区别 1.after的用法小结 1. 用作介词，与一段时间连用表示“在…之后”时，注意它与in的区别：after表示以过去时间为起点的一段时间以后，且通常与过去时态连用；而in则表示以现在为起点的一段时间以后： He came backafter two days. 他两天后就回来了。 He will come back in twodays. 他过两天就回来。 但after 若是与一点时间连用，则可与过去时态也可与将来时态连用： H e came back after 4 o’clock. 他是四点钟以后回来的。 He will come back after next month. 他将在下个月以后回来。 2. 用作连词引导时间状语从句时注意：若主句用将来时态(或含有将来意味)，则时间状语从句要用一般现在时态(表将来意义)，而不能直接使用将来时态：他回来后我就走。 正：I’ll leave after he comes back. 误：I’ll leave after he will come back. 3. 用作副词，表示“后来”、“ (一段时间)以后”，通常放在表示时间的副词之后：soon after 不久以后 two days after 两天后 4. 用于习语after all 终究，毕竟： I was right after all. 毕竟我是对的。 After all, he’s only six years old. 毕竟，他才六岁。 2.Before的用法小结 高三课本第十五单元，INTER GATING SKILLS 和WORKBOOK READING部分有如下的句子： ⒈The shop was successful，but it was about sixty years before people started to buy jeans for fashion as well as for work. ⒉However，it probably will not be long before the other mountainous areas of China such as Sichuan，Xinjiang and Yunnan are developed，and as more facilities become available，prices will almost certainly fall. 其中涉及到before的用法，下面就其用法进行总结。 一、可以用作介词 ⒈)指时间上早于，在……之前，如： She has lived here since before the war. 她从战前就一直在这儿住。 ⒉)指位置在前面，如：
动词三单形式和句型 转换讲解
小学英语动词的三单形式讲解 大家都知道，在一般现在时中，当主语是第三人称单数时，谓语动词要用第三人称单数形式，即常在动词原形后加-s或-es。但有些同学们对于哪些主语是第三人称单数还不十分清楚，现归纳总结如下：一、人称代词he, she, it是第三人称单数。如： He likes watching TV. 他喜欢看电视。 She has lunch at twelve. 她十二点吃午餐。 It looks like a cat. 它看起来像只猫。 二、单个人名、地名或称呼作主语；是第三人称单数。如： ① Han Mei looks like her mother. 韩梅看起来像她的母亲。 ② Beijing is in China. 北京在中国。 ③ Uncle Wang often makes cakes. 王叔叔经常做蛋糕。 三、单数可数名词或"this / that / the+单数可数名词"作主语时，是第三人称单数。如： ① A horse is a useful animal. 马是有用的动物。 ② This book is yours. 这本书是你的。 ③ That car is red. 那辆小汽车是红色的。 ④ The cat is Lucy's. 这只猫是露茜的。 四、不定代词someone, somebody, nobody, everything, something等及指示代词this, that作主语时，是第三人称单数。如： ① Everyone is here. 大家到齐了。 ② There is something wrong with the watch. 这块手表有毛病。 ③ This is a pen. 这是一支钢笔。 ④ That is a rubber. 那是一块橡皮擦。 五、不可数名词作主语时为第三人称单数。如： ① The milk is in the glass. 牛奶在玻璃杯里。 ② The bread is very small. 那面包很小。 六、当数字或字母作主语时，看作第三人称单数。如： ①"6" is a lucky number. "6"是个吉利数字。 ②"I" is a letter. "I"是个字母。 第三人称单数形式的构成 1. 一般直接在词尾加 s，如：work-works live-lives make-makes 2. 以s,x,ch ,sh等结尾的单词加 es , 如： miss-misses fix-fixes finish-finishes teach-teaches 3.以辅音字母加y结尾的单词，变y为i加 es , 如： fly-flies
It is +时间段+ since从句和It was / will be + 一段时间 + before从句 1.表示过去的情况 在“It is +时间段+ since从句(从句用一般过去时)”句型中， 如果since从句的谓语动词是瞬间性动词，表示肯定意义；如果since从句的谓语动词是延续性动词，则表示否定意义。 1) It is / has been ten years since he left Beijing. 自从他离开北京已经十年了。 分析：since从句中的left是leave的过去式，是瞬间性动词，表示肯定的意思，left译为“离开” 2) It is / has been ten years since he was a doctor. 他不当医生已经十年了。 分析：since从句中的系表结构表示一种状态，这种状态是延续性的，表示否定意义，译为“不是，不当” 注：时间的计算一律从since从句的动作完成或状态结束时算起。 2.表示过去的情况 “It was+ 一段时间 + since从句(从句用过去完成时had done)”，主句用一般过去时，从句用过去完成时； “It had been + 一段时间 + since从句(从句用一般过去时)”即主句用过去完成时，从句用一般过去时。 It was three years since Jack had been a teacher. 杰克不当老师已经三年了。 3. It was / will be + 一段时间 + before从句 1) 在“It was + 一段时间 + before从句”句型中，若主句是一般过去式，从句也是一般过去式时： ①若主句是肯定句，翻译成“过了多长时间之后才……” It was long before they found their son. 过了很久他们才找到他们的儿子。②若主句是否定形式，翻译成“没过多久就……” It was not long before the couple met again. 没过多久这对夫妻就见面了。 2) 在“It will be + 一段时间 + before从句”句型中，若主句是一般将来时，从句也是一般现在时： ①若主句是肯定句，翻译成“要过多长时间之后才……” 例： It will be half a year before I come back. 半年后，我才回来。②若主句是否定形式，翻译成“用不了多久就……” It won’t be long before we meet again. 我们不久就会见面。
现在完成时态中的since 与for 1. 实例： We have studied English for more than 2 years. 我们学英语已有两年多时间了。 She has been ill since last Sunday. 她从上周星期天一直病到现在。 2. 用法说明： (1) 介词for 短语表示一个时间段，指某个动作或情况到现在为止已持续了多久，提问时用how long；since 作为介词，接一个时间名词，作为连词，引导一个时间状语从句(从句动词一般是短暂性动词)，since 表示“自…以来”，指某个动作或情况从过去某一点时间一直持续到现在，因此，与for 或since 引出的时间状语连用的句子(或主语)谓语动词必须是持续性的(如上面两句中的动词study 和be) (2) 英语中有些动词的意义不能持续，表示的是一瞬间就结束的动作，这些动词被称为非持续性动词或短暂性动词，常见的如come, leave, go, lose, see, begin, start, arrive, bec ome, die, buy, borrow, close, join, reach, fall, get up 等。这类动词可以用于完成时态，但在肯定句中不能与表示动作延续的时间状语for 或since 短语连用。如：正：He has come back. 他已回来。 误：He has come back for three days. 若要表示“他回来已三天了”这样的意思，可以将动词改为延续性动词，或改变时间状语，或改用别的句型等，如译为： He has been back for three days. (改变谓语动词) He has been back since three days ago. (改变谓语动词) He came back three days ago. (改变时间状语及动词时态) It’s three days since he came back. (改变句型) (3) 非持续性动词用于完成时态，在肯定句中不能与for 或since引出的短语(或句子)连用，但在否定句中是可以的，因为一个非延续性动词一旦被否定即成为状态，而状态总是可以延续的。如：(https://www.doczj.com/doc/b84630123.html,) I haven’t seen him for a long time. 我很久没见到他了。 He hasn’t come here for some time. 他有段时间没来了。 I haven’t heard from her since she left. 自他离开以后，我一直没收到她的来信。
1.These are Mrs Wang?s shadows. （根据划线提问） __________ __________ are __________? 2.The tall trees are on the hill （改为一般疑问句） __________the tall ___________ on the ___________? 3. Is that a long bench?（改为复数句） __________ __________ long __________? 4. The paths are very long. （改为否定句） The __________ __________ very __________. 5. Is it a bench? Is it a chair?（改为选择疑问句） ___________ ___________ a bench __________ a chair? 6. What colour are the lawns?（根据实际情况回答） ___________ ___________. 1. Kitty likes playing football.（改为一般疑问句，并做否定回答）_______________________________________________ 2. My teacher likes talking with us.（改为否定句） _______________________________________________ 3. Dancing is my hobby. （根据划线部分提问） _______________________________________________ 4. new, school, is, club, in, there, a, our （连词成句） ________________________________________________ 5. I never go to school in July. （用Danny替换I，其他部分做相应改变）
before句型辨析与解析 It + will be + 时间段+ before等表示“在……之后……才”的句型总结 一、用于句型“It + will be + 时间段+ before...”句型中，表示“要过多久才…”，也可用于“It + may be + 时间段+ before...”，表示“也许要过多久才……”。Before 后的句子中用一般现在时态。 其否定形式“It will/would not be +时间段+ before…”表示“不久就……，过不了多久就……”。 （1）The field research will take Joan and Paul about five months; it will be a long time _____ we meet them again. A. after B. before C. since D. when （2）—How long do you think it will be ______China sends a manned spaceship to the moon? —Perhaps two or three years. A. when B. until C. that D. before （3）It ________ long before we _______ the result of the experiment. A. will not be...will know B. is...will know C. will not be...know D. is...know (4) Scientists say it may be five or six years_________ it is possible to test this medicine on human patients. A. since B. after C. before D. when 解析：答案为BDCC。考题 （1）(2)before 用于肯定的“It + will be + 时间段+ before...”句型中，表示“要过多久…才…”。 （3）before在本题中用于否定句,意为“过不了多久就会……”, 状语从句要用一般现在时代替一般将来时，可知C项为正确答案,句意是:要不了多久我们就会知道试验的结果了。 （4）宾语从句中含有句型“It + may be + 时间段+ before...”，表示“也许要过多久才……”，故选择答案C。 二、用于句型“it was +时间段+ before …” 表示“过了（多长时间）才……”。其否定形式“ it was not +时间段+ before …” 意为“不久就……”, “没过（多长时间）就……”。 It was some time ___________we realized the truth. A. when B. until C. since D. before 解析：答案为D。before用于句型“it was +时间段+ before …” 表示“过了（多长时间）才……”。该题题意是“过了一段时间我们才意识到事情的真相”。故正确答案为C项。 表示“在……之后……才”。副词“才”在汉语中强调某事发生得晚或慢。如果在含有before从句的复合句中，强调从句动作发生得晚或慢时，就可以应用这种译法。 The American Civil War lasted four years _______ the North won in the end. A. after B. before C. when D. then 解析：答案为B。本题考查连词before表示“在……之后才……”之的用法，根据本句含义“美国南北战争持续了四年，北方才最终取得胜利”，可知本题应选B。 三、表示“……还没来得及……就……”。目的在于强调从句动作发生之前，主句动作已发生。 —Why didn't you tell him about the meeting? — He rushed out of the room _________ I could say a word. A. before B. until C. when D. after 解析：答案为A。本题考查连词before表示“……还没来得及……就……”的用法。句意是“我还没来得及说一句话，他就冲出了房间”。 四、表示“在……之前就……”。这时主句与before从句中的两个动作按时间先后依次发生。 It was evening______ we reached the little town of Winchester. A. that B. until C. since D. before 解析：答案为D。本题考查连词before表示“在……之前就……”的用法。句意是“我们到达小镇Winchester 之前就已经是傍晚时分了”。 五、表示“趁……”，“等到……”，或“没等……就…… ”等。
否定句：be动词（am、is、are）+not、 情态动词can+ not、 助动词（do、does） + not 如何将一个肯定的陈述句改为否定句： 1、看句中有无be动词，如有，直接在be动词后+ not。 2、看句中有无情态动词，如有，直接在情态动词后+ not。 3、如上述二者都没有，就应用助动词+ not。分四个步骤： （1）肯定陈述句中本来是没有助动词的，要加上去，位置在主语（某人或某物）后，动词前。 （2）确定助动词用do、does，根据句中动词，动词是原形的助动词就用do，动词是第三人称单数的助动词就用does， （3）在助动词后加not。 （4）原句中动词假如发生变化就要恢复成原形。 强调一点，有some的要考虑是否要用any。 1.I am Tom. _____________________________ _ 2.He is nine. ____________________________ __ 3.They are pupils.______________________________ 4.I can fly a kite. ______________________________ 5.He can make a toy. ______________________________ 6.You must go home now.______________________________ 7.I like Jinan. 8.He likes swimming. 9.He has many books. 10.He has some books. 11.There is a pen on the desk. 12.There are some water in the glass. ______________________________ 13.You have got some books. ___________________________________ 14.You have some books. 15.He has got some apples. 16.He has some apples. _________________________________________ 17.I like to watch TV. ______ . 18.Xiao Fang and I go to the library everSaturday. . 19.Tim swims very well. ___________ . 20.Mr. Smith has many books about the cars. . 21.I want to play with my friends. . 22.We feel cold today. _____________ . 23.Bob reads English everyday. . 24.We do our homework at school. . 25.Mr. White has two houses. .