九年级英语Unit13《We're trying to save the earth!》知识点1.现在进行时定义：表示说话时（瞬间）正在进行的动作，也表示目前或现阶段一直进行的动作。
结构: ①肯定句: 主语+ am/is/are + V-ing②否定句: 主语+ am/is/are + not + V-ing③疑问句: Am/Is/Are + 主语+ V-ing用法：1）表示说话时正在进行的，目前正在发生的动作。
①Look! The big bird is flying away. ②He is watching a movie now.2）表示目前一段时间内正在进行，但说话时可能没有进行的动作。
Right now I am studying Chinese by distance learning. 我现在正通过远程教育学习汉语。
1) 2)常带有表示目前时刻的时间副词, 如：now, right now, at the (very) moment, for the time being, at present, these days 及Look! Listen! ...3）与always, constantly, forever, all the time等副词连用，表示动作反复或习惯。
此时句子常含有说话者的强烈情感在内。
表达较强的“责备”或“表扬”之意①You are always changing your mind. 你总是主意不定。
(太烦人了)②He is always helping others.他总是帮助别人。
(他真是个好人)4）对于come, go, leave, arrive, start, fly, drive等表示位置移动的动词常可用进行时态表将来。
①He is leaving on Wednesday.②Mary isn’t here at the moment. She is coming later.2. used to do过去常常做某事见第四单元及use用法be/get used to doing 习惯于做某事be used to do=be used for doing 被用来做某事3. 被动语态见第五单元注意：接双宾语的词的被动语态；make /let /have sb do的被动语态；see/ hear /notice /find /observe/notice sb do 的被动语态；It’ssaid/reported/believed/supposed/well-known that；及无被动语态的三种情况（感官动词、不及物动词、sell/write等）4. 现在完成时:用法：①过去发生的动作对现在造成的影响或结果：强调结果Yesterday I finished my homework, that’s to say, I have finished my homework now.②过去已经开始一直持续到现在的动作或状态：强调继续I have lived here since 1990.现在完成时的构成have/has+过去分词现在完成时的四个基本句型肯定句He has finished the work.一般疑问句Has he finished the work?否定句He has not finished the work.两回答Yes ,he has. No, he hasn’t.特殊疑问句What has he done?在下列情形下用现在完成时1九词语①already 已经肯定句中或句尾I have already found my pen. = I have found my pen already.②yet已经否定句和疑问句句尾I have not finished the work yet.Have you bought a computer yet?③ever曾经句中Have you ever seen pandas?④never从不句中I have never been to Beijing.⑤just刚刚句中I have just done my work.⑥before以前句尾I have never been there before.⑦so far到目前为止So far he has learned 200 words.⑧how long多久How long have you lived here?⑨how many times多少次How many times has he been to Beijing?2两词组have<has>gone to去了某地例：He has gone to Beijing (去了北京，没回) have<has>been to去过某地例：He has been to Beijing. (去过北京，回了)精品文档3两结构for two months for +一段时间 Jim has lived here for 2 months.since last year since +过去时间点 Lucy has been in Beijing since 3 years ago. since 3 years agosince 1990since he came here since +过去时态句子 He has been in China since he came here.4如果句子里面没有时间状语，汉语意思能够加“已经”，往往用现在完成时态。
Have you lost your library book? 你已经弄丢了从图书馆借的那本书吗？5现在完成时态还常常用于下列句型They have planted many trees in the last/past few years.This is the best book I have ever read.It is the first time I have played the computer games.在现在完成时中，一次性动词不能和一段时间状语连用例：He has bought the book for 3 years.（错）因buy这个一次性动词不能和一段时间for 3 years连用, 改正的办法有：He has bought the book. (去掉一段时间for 3 years)He bought the book 3 years ago (改为一般过去时，使句子的意思不变)It’s/It has been 3 years since he bought the book. = 3 years has passed since he bought the book. （改为固定句型It is/It has been ---since---）He has had the book for 3 years.（用延续性动词have代替buy）另外①com e/arrive/get to/reach → be here I have come here for 3 years.（错）改为：I have been here for 3 years.②leave/go →be away He has left for 3 hours.（错）改为：He has been away for 3 hours.③begin/start →be onThe film has begun for 3 minutes.（错）改为：The film has been on for 3 minutes.④open →be open / close → be closedThe shop has opened for 3 years.(错)改为：The shop has been open for 3 years.⑤die →be deadHis father has died for 3 years.(错)改为：His father has been dead for 3 years.⑥finish/end→ be overHe has finished the work for 3 days.(错)改为：The work has been over for 3 days⑦join I have joined the army for 3 years.（错）改为：I have been in the army for 3 years.或I have been a soldier for 3 years.⑧buy /catch → haveI have bought the bike for 3 years.（错）改为：I have had the bike for 3 years.He has caught a cold for 3 days.（错）改为：He has had a cold for 3 days.⑨borrow → keepI have borrowed the book for 3 years. （错）改为：I have kept the book for 3 years.还有其它的归纳如下：break → be broken get up → be up marry → be married become → be lose → be lost5. 情态动词1) 情态动词本身有一定的词义，表示说话人的情绪、态度或语气，但不能单独作谓语，只能与其他动词构成谓语。
常见的有：can (could), may (might), must, need, shall (should), will (would)等。
2) 情态动词无人称和数的变化, 后接动词原形。
否定式是在情态动词后面加not。
个别情态动词有过去式形式, 也可用来表达更加客气、委婉的语气。
精品文档1.can和could的用法(1)can/could 表示“能力；许可；可能性”等。
could 为can 的过去式。
如：Can I use your bike?(2)can 用在疑问句中，表示征求意见、请求许可，答语仍用can; could 用在疑问句中，比can 更委婉、客气，是一种礼貌的说法，并不表示过去时态，答语用can，而不能用could。
如：—Could you tell me the way to the zoo?—Sorry. I can't. I'm new here。