2018年公共英語四級重點語法資料：表推測的用法
2018年公共英語四級重點語法資料：表推測的用法
表推測的用法
1、must have done
表示對過去某事的肯定猜測，譯為：過去肯定做了某事。不存在mustn’t have done的形式。其否定或疑問形式須用can(could)來表示。例如：
Since the road is wet, it must have rained last night.既然路是濕的，那昨天晚上肯定下雨了。
He can’t have missed the way. I drew him a map.他不可能迷路。我(當(dāng)時)給他畫了張圖。
2、may/might have done
May/might have done表示“過去可能做了某事”。may比might 表示的可能性在說話人看來稍大些。may/might not have done表示“過去可能沒有做某事”。例如：
I can’t find my keys. I may/might have left them at the school yesterday.
我找不到我的鑰匙了。我可能昨天把他們落在學(xué)校了。
John may/might not have passed the exam, he looks very sad.
John可能沒有通過考試。他看起來很憂傷。
注意：may/might have done表推測不能用于疑問句中。
3、can/could have done表推測，一般用在否定句和疑問句中，表示不相信或懷疑的態(tài)度。
Can/Could he have passed the exam?他可能通過考試了嗎?
I think that he couldn’t/can’t have gone abroad. I saw him just now.
我認為他不可能出國了。我剛才還看見他了。
注：表示推測過去某動作發(fā)生的可能性是，就表示的可能性程度而言，must最大，could其次，may更次之，might最小。例如：
I wonder how Tom knew about your past.我想知道Tom是怎么知道你的過去的。
He must/could/may/might have heard of it from Mary.
他肯定/很可能/可能/也許已從Mary那兒聽說此事了。
5、動詞不定式
1、不定式做主語一般表示具體的某次動作。
To complete the 30-storied building in one year was quite a difficult task.
To do that implies taking responsibility.
當(dāng)主語較長，謂語較短時，常用it做形式主語，而將不定式放到謂語的后面。如：
It is important for modern young people to master at least two foreign languages.
It做形式主語，不定式放在謂語動詞之后常用于下列結(jié)構(gòu)中：
A. It is+形容詞+(for/of sb.)+不定式，如：
It is not easy to catch fish with your hands only.
It is important for us young people to learn English and master it.
B. It is+名詞+不定式
It is a pity to have to go without her.
C. It takes (sb.) some time +不定式
It takes me three hours to learn English each day.
2、不定式作表語
不定式作表語常表示將來的動作，主語常常是表示意向、打算、計劃的詞(idea, task, purpose)等,如：
The most important thing for one’s health is to have plenty of exercise.
3、不定式作賓語
I like to go out for walks in the warm sunshine in spring.
She failed to finish the assignment in time, and she was worried about it.
4、“wh-+不定式”結(jié)構(gòu)
不定式前加一個疑問代詞(what, which, who, whom, whose)或疑問副詞(where, when, how, why)，以及連詞whether構(gòu)成特殊的不定式短語，其作用相當(dāng)于一個從句，這樣的不定式短語常常在某些動詞后面作賓語。
I couldn’t decide which book to choose.
I can tell you where to get this book.
“wh-word+不定式”結(jié)構(gòu)除了作賓語外，還可以在句中作主語或者表語。如：
When to start the program remains undecided.
The question is how to put the plan into practice.
5、不定式作狀語
A.不定式作狀語表示目的�；蛴糜趕o as和in order之后，來強調(diào)這種目的。如：
To learn a foreign language well, you must make painstaking efforts.
B.不定式表示結(jié)果，特別是在so…as to, such…as to, only to…以及too…to等結(jié)構(gòu)中的不定式表示結(jié)果。如：
She left her hometown with her beloved man, never to return.
No one is too old to learn.
Would you be so kind as to carry the luggage for me?
C.不定式常用來修飾形容詞，構(gòu)成詞組，如：
It is likely to rain today, for it is very cloudy.
I am willing to help you with your homework, for we are friends.
6、不定式作賓語補語不定式長跟在動詞之后作賓語補語，如：
He asked you to call him at ten o’clock.
I’d never allow my children to behave like that.
當(dāng)不定式在let, make, have, 感官動詞后面作賓語補語時，不定式不帶to。如：
Whenever something is wrong with you, please do let me know.
I will have the students write a passage about Internet.
7、不定式作定語
A.不定式作定語通常要放在其所修飾的名詞或代詞之后。不定式常作名詞定語，如：
His efforts to carry out the plan were successful.
There is no need to bother him with such trifles.
B.由only, last, next, 序數(shù)詞或形容詞最高級修飾的名詞常用不定式作定語。如：
Mr Zhang is always the first man to arrive at the office and the last man to leave.
I don’t think he is the best one to do the work.
8)不帶to的不定式在下列詞組后面的不定式不帶to：
would rather…than(寧愿…也不)，had better…(最好)，can’t help but…(不得不)，had rather…(寧愿)，cannot but…(不得不，必然)，may/might as well…(不妨)，let alone(更不用說)。如：
I can’t help but wish that nothing would go wrong.
They had never seen such delicious food, let alone eat it.
9)不定式的完成式to have done表示在謂語動詞之前已經(jīng)發(fā)生的動作，而不定式的一般式to do表示動作將要發(fā)生。不定式還有其被動形式：to be done(表示將來的被動動作)和to have been done(表示過去的被動動作)。
6、動名詞
1、在某些動詞后面只能用動名詞，如：
He hasn’t finished reading the novel. 他還沒有看完那部小說。
We must practice speaking English. 我們必須練習(xí)講英語。
2、 某些動詞后接動名詞與接不定式意義不同。如：
He stopped singing.他停止唱歌。 She tried pushing the door.她試著推門。
He stopped to sing.他停下來去唱歌。 She tried to push the door.她試圖把門推開。
She remembered posting (having posted) the letter at the post-office.
她記得在郵局寄了那封信。
She remembered to post the letter at the post-office.
她記得要在郵局寄那封信。
3、 下列短語中的to是介詞，其后跟動名詞，不跟不定式。
be(get) used to 習(xí)慣于;look forward to 盼望;pay attention to 注意;get down to 開始認真做;lead to 通向、導(dǎo)致;prefer doing…to doing… 寧愿做…而不愿做…;stick to 堅持;devote one’s life(time, oneself) to 獻身于、致力于;object to 反對;in addition to… 除…之外;on the way to… 在去…的路上、正要成為…
4、 在動詞need, want, require后面，用動名詞的主動形式表示被動的意義。用不定式時要用它的被動形式，如：
The house needs repairing. 房子需要修理
5、 be worth后面的動名詞用主動形式表示被動含義，如：
The book is worth reading. 這本書值得讀一讀。
6、 一些動詞短語如feel like, can’t help等后需要接動名詞，如：
I don’t feel like going to see a film. 我不想去看電影。
The child couldn’t help laughing when he saw the monkey.這孩子看到猴子不禁笑了起來。
7、 動名詞除了其一般式doing，還有完成時having done以及一般式的被動形式being done和完成式的被動形式having been done;動名詞前可以加上邏輯主語，構(gòu)成動名詞的復(fù)合結(jié)構(gòu)：one’s doing。例如：
I’m sorry for not having kept my promise. 非常抱歉，我沒能遵守諾言。
(not having kept my promise發(fā)生在am sorry之前)
Do you mind Mary being left alone at home? 你介意Mary被單獨一個人留在家里嗎?
7、主謂一致
1、主語是抽象概念短語或從句作主語時，謂語用單數(shù)形式。
Collecting stamps is my favorite hobby.(動名詞短語作主語)
That we have made such progress is a fact.(從句作主語)
2、what或which引導(dǎo)的主語從句的句子，謂語動詞或系動詞與表語的數(shù)一致。
What I want is a new bicycle. Which are your pictures?
3、兩個以上的主語用and或both連接時，謂語用復(fù)數(shù)形式。例如：
Both Tom and Dick are good friends.
4、and所連接的兩個詞如指同一主體時，謂語則用單數(shù)形式。例如：
A singer and dancer was present at the party today.
A singer and a dancer were present at the party today.
5、集體名詞作為整體意義時，謂語用單數(shù)形式，若指成員意義時，謂語則用復(fù)數(shù)形式。例如：
My family is a big one. My family are watching TV now.
6、主語是單數(shù)后面跟有as well as, with, together, like, but, except等短語時，謂語動詞仍用單數(shù)形式。
(1)Kelly as well as the other students has learned how to type.
(2)Our school, with some few schools, was built in the 1960s.
7、兩個主語由not only…but also, either…or, neither…nor相連接時，在肯定句中謂語變化取決于后者，在疑問句中取決于前者，例如：
Not only my parents but also my teacher has been to the party.
Either he or I am to go there.
Neither the students nor the teacher likes the film.
8、 people, police, cattle(牛群), militia(民兵)作主語時，謂語用復(fù)數(shù)形式。例如：
The police are still running after the murderer.
The cattle are grazing(放牧) in the fields.
9、 half of+單數(shù)名詞時，謂語用單數(shù)形式;half of+復(fù)數(shù)名詞時，謂語用復(fù)數(shù)形式。例如：
Half of the apple is rotten. Half of the apples are rotten.
10、書名、國名等名詞作主語時，謂語用單數(shù)
Hamlet was written by Shakespear.
The United States is a large country.
11、each, either, neither等代詞作主語時，謂語動詞為單數(shù);both做代詞主語時，謂語用復(fù)數(shù);none接不可數(shù)名詞作主語時，謂語動詞用單數(shù)，接可數(shù)名詞復(fù)數(shù)時謂語單復(fù)均可。
12、the+形容詞作主語時，謂語用復(fù)數(shù)形式。
The rich are not always happy though they have much money.
13、成對名詞作主語時，謂語用單數(shù)形式，需要用冠詞時只用一個，例如：
A knife and fork is on the table. Success and failure is common in life.
14、復(fù)合不定代詞及many a+名詞作主語時，謂語用單數(shù)形式。(表示復(fù)數(shù)意義)例如：
Everyone says it is a good film. Many a student likes it.
15、金錢、時間、重量、長度和距離等名詞的復(fù)數(shù)形式作主語，謂語用單數(shù)變化。例如：
Five minutes is enough. 100 dollars seems to much for the coat.
16、who, which, thar引導(dǎo)定語從句作主語時，謂語變化取決于其代表的先行詞的數(shù)，例如：
He is one of the students who were late this morning. All that glitters is not gold.
17、more than one+名詞作主語時謂語用單數(shù)形式。例如：
More than one student was late today. More than one has learned about it.
18、分數(shù)或百分數(shù)后接單數(shù)名詞作主語時，謂語用單數(shù)形式，接復(fù)數(shù)名詞時，謂語用復(fù)數(shù)形式。例如：
About thirsty percent of my sister’s books are in English.
Two-thirds of the furniture in this room was bought last week.
80%(Four-fifths) of the students are boys.
19、“there be+并列主語“和”here be+并列主語“結(jié)構(gòu)中的謂語形式一般應(yīng)與并列主語中的第一個主語的數(shù)一致。
There is a pen and two books on the desk. There are some books and a pen on the desk.
