Infinitive 不定式

不定式在句中充當結構

在句中可作除謂語以外的一切成份：主、表、賓、定、狀、（主、賓）補語。

1. 不定式作主語

To say something is one thing, to do it is another.

It is not fair to blame them for the accident. （it 形式主語）

2. 不定式作表語

My suggestion is to carry out the plan immediately.

The question is how to organize the work. （不定式的特殊結構，見后）

3. 不定式作賓語

He offered to go with us.

I don't know where to get the books.

（不定式的特殊結構，見后）

常跟to do(不定式) 作賓語的v:

afford, agree, arrange, ask, attempt, beg, care, choose, claim（聲稱）,dare, decide, decline（謝絕）,desire, determine, fail, intend, learn, long, mean, offer, pretend, promise, refuse, seek, tend, undertake（承擔）, volunteer.

不定式的特殊結構

構成：疑問代詞、副詞及whether / if + to do

常跟疑問代詞、副詞及whether / if + to do作賓語的v.有

ask, consider, decide, discover, discuss, explain, find out, inquire, forget, know, learn, remember, show（演示）,tell, think, understand, wonder.

Examples:

I still don't know whom to turn to for help.

They are trying to find out how to solve the problem.

Show me where to put the books.

They haven't decided yet (as to) whether to accept our offer of help.

如果不定式作賓語又跟有補語，通常要用“it”作形式賓語，而將不定式放到補語后面去。

eg. 他們發現提前做好一切準備是不可能的。

They found it impossible to get everything ready in advance.

I consider it my duty to point out their shortcomings.

4. 作賓/ 主語補足語

Mr. Smith wants his son to become a lawyer.

The suspected man was seen to enter the building.

跟不帶“to”的不定式作賓補的v:

see, hear, look at, listen to, feel, observe, watch, notice 等感官v 及let, make, have, keep.

The teacher makes us write a composition every week.. （被動語態中要加上“to”）

不定式的復合謂語結構

復合謂語結構:（兩個或多個部分構成復合謂語，如:He can do it）

(1) be said (reported, known, believed, announced, claimed, stated,…) + to do

=>It is said ... that …

Beijing is known to have rich cultural heritage.

(It is known that Beijing has ...)

(2) seem（happen, appear, prove, tend）+ to do

I happened to be out when she called.

(3) be likely（certain, sure, willing, anxious, ready, bound, eager, reluctant) +to do

They are likely to succeed.

She is always ready to help others.

5. 不定式作定語

通常為后置修飾語:（post-modifier）

He used to have a lot of meetings to attend.

There is nothing to worry about.

6. 不定式作狀語

(1)目的狀語

He hurried through his work so as to（in order to）catch the train.

They will go to the station to meet the guests.

To survive the severe competition in the future society, one must have all-round abilities.

(2)不定式作狀語:結果狀語

She was so angry as to be unable to speak.

I hurried to Prof. Wang's house only to find he was out.（常表示令人不快的結果）

(3)不定式作狀語:原因狀語

We are overjoyed to see you.

I am happy to be here.

I feel honored to give a speech here.