九年级英语Unit13《We27retryingtosavetheearth!》知识点.doc

九年级英语Unit13 《 We27re trying to save the earth!》知识点

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.

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 bo ught 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

①

（错）

改为： I have been here for 3 years.

②leave/go →be awa y

He has left for 3 hours.（错）

改为： He has been away for 3 hours.

③ begin/start→be on

The film has begun for 3 minutes.（错）改为： The film has been on for 3 minutes.

④ open →be open / close→ be closed

The shop has opened for 3 years.(错)

改为： The shop has been open for 3 years.

⑤ die→be dead

His father has died for 3 years.(错)

改为： His father has been dead for 3 years.

⑥ finish/end→ be over

He has finished the work for 3 days.(错)

改为： The work has been over for 3 days

⑦ join 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.

⑧ buy /catch→ have

I 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 → keep

I 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：

5.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,

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。

shall (should), will (would)

1.can 和 could 的用法

(1)can/could 表示“能力；可；可能性”等。 could can 的去式。如： Can

I use your bike?

(2)can 用在疑句中 ,表示征求意、求可,答仍用can; could 用在疑

句中 ,比 can 更委婉、客气 ,是一种礼貌的法, 并不表示去 ,答用 can, 而

不能用 could 。如：—Could you tell me the way to the zoo? — Sorry. I can't. I'm new here 。

[注意 ] can 和 could 只能用于在和去两种,将来中用 be able to。另外 , can't 可表示否定推。如： That ______ be Mr Wang. He has gone

to Beijing 。

2.may 和 might 的用法

may/might 意“可以”,表示同意、可或求方可,也可表示祝愿。 may 的否定形式may not 。 might 是 may 的去式 ,有两种用法：一种表示去式；

一种表示虚气,使气更加委婉、客气,或表示可能性更小。以may 开的一般疑句 ,其否定回答用mustn't,而不用may not 。如： ______ I use your pen? 我可以用你用的笔？

You may put on more clothes. May you be happy!

Might I borrow some money now?He might be alive.

3.must 的用法

must意“必,一定,准是”,表示人有必要做某事, 或命令、要求人做某事以及事物的推。否定形式mustn't,表示“不得”一,“定不要”。如：

I ______ finish my work today。You mustn't drive after drinking。

(1)must 与 have to 的区： must 表示人的主意愿； have to 表示客需要。如：

I must do my homework first。It is raining hard outside; I _____ stay at

home 。

(2)回答由 must 引的疑句的提①肯

定回答： Yes, ⋯must. 如：

— Must I go home now? — Yes, you must. ②否定回答：No,⋯needn't./No,⋯don't/doesn't have to.

— Must I go home now? — No, you __ ____.

(3)must 表示事物的推 ,意“想必；一定”,只用于肯定句中；表“推” ,情与原

形 ,(常 be )用 ,如： The man must be our teacher 。

4.need 的用法

(1)need表示“需要,必”,主要用于否定句和疑句中。其否定形式needn't, 表示“没有必要 ,不必”；由 need 构成的疑句行回答 ,其肯定回答用 must, 否定回答用needn't 。如

— Need we do some cleaning now?

— Yes, you must. — No, you needn't.

(2)need可作,常用于下列构：

①人： need to do sth“需要做某事”。如I need to learn more.

②物： need doing“某物需要被做”=need to be done。

如： My hair needs cutting. =My hair needs to be cut.

③ need + 名或代。如：All living things need water.

5.shall 和 should 的用法

shall 用于第一人称的句子中,表示提建或求；should 用于各种人称的句子中,或任 ,意“ ”。如： ______ we go out for a walk?

You should study hard at school。

should have done主要有两个用法：

用于推去已生的情况。如：He should have arrived by now.

用于指本生而上未生的情况。如：You should have told me so before.

6.will 和 would 的用法

will 用于第二人称疑句,表示征求意或提建；would will 的去式 ,可用于多种人称,表示意愿。如：Will you have a little soup?

would have done主要有两个用法：

表“猜去”

I guess the poet would have been about twenty when she wrote her first poem.