现在完成时
现在完成时用来表示之前已发生或完成的动作或状 态，其结果的确和现在有联系。动作或状态发生在过去 但它的影响现在还存在；也可表示持续到现在的动作或 状态。其构成： have (has) +过去分词。 用于现在完成时的句型
1）It is the first / second time?. that?结构中的从句部分，用现在完成时。 It is the first time that I have visited the city. 2）This is the? that?结构，that 从句要用现在完成时.
This is the best film that I've (ever) seen. 这是我看过的最好的电影。 3）最基本句型 主语+have/has+（already/just）+动词的过去分词+其他 注意：非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是可以持续的。 （错）I have received his letter for a month. （对）I haven't received his letter for almost a month.
比较since和for Since 用来说明动作起始时间，for用来说明动作延续时间长度。 I have lived here for more than twenty years. I have lived here since I was born..
注意：并非有for 作为时间状语的句子都用现在完成时。
I worked here for more than twenty years. (我现在已不在这里工作。) since的四种用法
1) since +过去一个时间点 (如具体的年、月、日期、钟点、1980, last month, half past six)。 I have been here since 1989.
2) since +一段时间+ ago I have been here since five months ago. 3) since +从句 Great changes have taken place since you left. 4) It is +一段时间+ since从句 It is two years since I became a
postgraduate student.
5）since和for 在现在完成时态，since后面加时间点，for后面加时间段。 延续动词与瞬间动词
1) 用于完成时的区别 延续动词表示经验、经历； 瞬间动词表示行为的结 果，不能与表示段的时间状语连用。
He has completed the work. 他已完成了那项工作。 (表结果) 2) 用于till / until从句的差异
延续动词用于肯定句，表示\做??直到??\瞬间动词用于否定句，表示\到??，才??\He didn't come back until ten o'clock. 他到10 点才回来。
过去完成时 1） 概念：表示动作发生在过去，并在过去完成（即是常说的过去的
过去）。 其基本构成是：had+动词过去分词。
2） 用法
a. 在told, said, knew, heard, thought等动词后的宾语从句。 She said (that) she had never been to Paris.
b. 状语从句 在过去不同时间发生的两个动作中，发生在先，用过去完成
时；发生在后，用一般过去时。When the police arrived, the thieves had run away.
c. 表示意向的动词，如hope, wish, expect, think, intend, mean, suppose
等，用过去完成时表示\原本?，未能?\We had hoped that you would come, but you didn't.
3) 过去完成时的时间状语before, by, until , when, after, once, as soon
as。 He said that he had learned some English before. 注意：had no ? when 还没等?? 就?? had no sooner? than 刚?? 就?? 将来完成时 1) 构成will / be going to do sth.
2) 概念
a. 状态完成：表示某事继续到将来某一时为止一直有的状态。
b. 动作完成：表示将来某一时或另一个将来的动作之前，已经完成的动作或一获得的经验。 They will have been married for 20 years by then.
现在进行时 现在进行时的基本用法：
a. 表示现在( 指说话人说话时) 正在发生的事情。
b. 习惯进行：表示长期的或重复性的动作，说话时动作未必正在进行。 c. 表示渐变的动词有：get, grow, become, turn, run, go, begin等。 d. 与always, constantly, forever 等词连用，表示反复发生的动作或持续存在的状态，往往带有说话人的主观色彩。 You are always changing your mind. 不用进行时的动词 1) 事实状态的动词 have, belong, possess, cost, owe, exist, include, contain, matter, weigh, measure, continue
2) 心理状态的动词 Know, realize, think see, believe, suppose, imagine, agree, recognize, remember, want, need, forget, prefer, mean, understand, love, hate 3 ) 瞬间动词 accept, receive, complete, finish, give, allow, decide, refuse. 4) 系动词 seem, remain, lie, see, hear, smell, feel, taste, get, become, turn
过去进行时
1） 概念：表示过去某时正在进行的状态或动作。
2） 过去进行时的主要用法是描述一件事发生的背景；一个长动作发生的时候，另一个短动作发生。
3) 常用的时间状语 this morning, the whole morning, all day yesterday, from nine to ten last evening, when, while
将来进行时
1) 概念：表示将来某时进行的状态或动作，或按预测将来会发生的事情。 注意：将来进行时不用于表示\意志\，不能说 I'll be having a talk with her. 2）常用的时间状语 Soon, tomorrow, this evening，on Sunday, by this time，tomorrow, in two days, tomorrow evening
一般现在时代替将来时时间状语从句，条件句中，从句用一般现在时代替将来时
When, while, before, after, till, once, as soon as, so long as, by the time, if, in case (that), unless, even if, whether, the moment, the minute, the day, the year, immediately
He is going to visit her aunt the day he arrives in Beijing. 他一到北京，就去看他姨妈。
(2) 表示现在已安排好的未来事项，行程等活动。
The museum opens at ten tomorrow. 博物馆明天10点开门。(实际上每天如此。)
一般现在时代替过去时
1 )\书上说\报纸上说\等 The newspaper says that it's going to be cold tomorrow 报纸上说明天会很冷的。
2) 叙述往事，使其生动。 Napoleon's army now advances and the great battle begins.
一般现在时代替完成时 1) 有些动词用一般现在时代替完成时： hear,
tell, learn, write , understand, forget, know, find , say, remember. I hear (= have heard) he will go to London.
2) 句型 \? since?\代替\? since ?\ 3) It is (= has been) five years since we last met.
一般现在时代替进行时 1) 句型：Here comes? ； There goes?
Look, here comes Mr. Li.
现在进行时代替将来时 1) 表示即将发生的或预定中计划好的活动。
We are leaving soon. 我们马上就走。
2) 渐变动词，如：get, run, grow, become, begin及die。 He is dying.
用一般过去时代替完成时
1) 两个动作如按顺序发生，又不强调先后，或用then，and，but 等连词时，多用一般过去时。 When she saw the mouse，she screamed.
2 ) 两个动作相继发生，可用一般过去时；如第一个动作需要若干时间完成，用过去完成时。 When I heard the news, I was very excited. 3) 叙述历史事实，可不用过去完成时，而只用一般过去时。 Our teacher told us that Columbus discovered America in 1492.
比较过去时与现在完成时 1）过去时表示过去某时发生的动作或单纯叙述过去
的事情，强调动作；现在完成时为过去发生的，强调过去的事情对现在的影响，强调的是影响。 2）过去时常与具体的时间状语连用，而现在完成时通常与模糊的时间状语连用，或无时间状语。 一般过去时的时间状语: yesterday, last week，?ago, in1980, in October, just now, 具体的时间状语
共同的时间状语: this morning, tonight,this April, now, once，before, already, recently，lately
现在完成时的时间状语 for, since, so far, ever, never, just, yet, till / until, up to now, in past years, always, 不确定的时间状语
3）现在完成时可表示持续到现在的动作或状态，动词一般是延续性的， 如live, teach, learn, work, study, know.
过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。I saw this film yesterday. （强调看的动作发生过了。）
语态有两种： 主动语态和被动语态。
主语是动作的发出者为主动语态；主语是动作的接受者为被动语态。
1）若宾语补足语是不带to 的不定式，变为被动语态 时，该不定式前要加\。此类动词为感官动词。 feel, hear, help, listen to, look at, make, observe, see, notice, watch
The teacher made me go out of the classroom.
--> I was made to go out of the classroom (by the teacher). 2）情态动词+ be +过去分词，构成被动语态。
Coal can be used to produce electricity for agriculture and industry. let 的用法
1）当let后只有一个单音节动词，变被动语态时，可用不带to 的不定式。 They let the strange go.---> The strange was let go.
2） 若let 后宾补较长时，let 通常不用被动语态，而用allow或permit 代替。 The nurse let me go to see my classmate in the hospital.
----> I was allowed / permitted to see my classmate in the hospital
短语动词的被动语态 短语动词是一个整体，不可丢掉后面的介词或副词。
My sister will be taken care of by Grandma.
表示\据说\或\相信\的词组 believe, consider, declare, expect, feel , report, say, see, suppose, think, understand
It is said that? 据说 It is reported that? 据报道 It is believed that? 大家相信 It is hoped that? 大家希望 It is well known that? 众所周知 It is thought that? 大家认为 It is suggested that? 据建议 It is taken granted that? 被视为当然 It has been decided that? 大家决定It must be remember that?务必记住的是