infinitive: use; after who, what, how; of purpose

infinitive: negative, progressive, perfect, passive

1    Negative infinitive:

not + infinitive

• Try not to be late. (NOT . . . to not be late )


• I decided not to study medicine. (NOT . . . to not study . . .)


• You d better not say that again.


• Why not tell me about your problems⁷

2   Progressive infinitive:

(to) be... -ing

• It's nice to be sitting here with you.


• This time tomorrow I'll be lying on the beach.

3   Perfect infinitive:  

(to) have + past participle

It's nice to have finished work.

Ann said she was sorry to have missed you

You should have told me you were coming.

For perfect infinitives after modal verbs (should, might etc), see 202.3.

4   Passive infinitive:   (to) be + past participle

• There's a lot of work to be done


• She ought to be told about it.


• That window must be repaired before tonight.

infinitive: use

1 Subject

An infinitive can be the subject of a sentence.

• To learn Chinese is not easy.


• It is not easy to learn Chinese.
  


• Learning Chinese isn't easy.

2 After verb

We often use an infinitive after another verb.

• It's beginning to rain


• I expect to be free tomorrow evening.
  


• I don't want to see you again.

Some common verbs that can have an infinitive after them:

afford	happen	prefer
appear	hate	prepare
arrange	help	pretend
ask	hope	promise
(can't) bear	intend	refuse
begin	learn	remember
dare (see 94)	like	seem
decide	love	start
expect	manage	try
fail	mean	want
forget	offer	wish

Some of these verbs can be used with  object + infinitive (for example I want her to be happy).

After some of these verbs, we can also use an -ingform.
The meaning is not always the same (for example, try running/try to run).

3   Verb + object + infinitive

After some verbs, we can use object + infinitive

• She didn't want me to go
  (NOT She didn't want that t go.)
  


• I didn't ask you to pay for the meal.

Some common verbs that are used in this structure:

advise	hate	prefer
allow	help	remind
ask	invite	teach
(can't) bear	like	tell
cause	mean	want
encourage	need	warn
expect	order	wish
get	persuade

4.After adjective

Infinitives are used after some adjectives.

• I'm pleased to see you.
  


• John was surprised to get Ann's letter.


• His accent is not easy to understand (NOT . . . to understand it)


• She's very nice to talk to (NOT . . . to talk to her.)

5. After noun

We can use infinitives after some nouns.

• I have no wish to change


• I told her about my decision to leave

The infinitive often explains the purpose of something: what it will do, or what somebody will do with it.

• Have you got a key to open this door?


• I need some more work to do

infinitive after who, what, how etc

1 In reported speech, we can use an infinitive after the question-words who, what, where etc (but not why) to talk about questions and the answers to questions.

verb + question-word + infinitive

• I wonder who to invite. Show me what to do.


• Can you tell me how to get to the station?
  


• I don't know where to put the car.
  


• Tell me when to pay


• I can't decide whether to answer her letter.

2 We cannot begin a direct question with How to . We often use shall or should.

• How shall I tell her? (NOT How to tell her?)
  


• What shall we do? (NOT What to do?)
  


• Who should I pay? (NOT Who to pay?)

infinitive of purpose

We often use an infinitive to talk about a person's purpose — why he or she does something.

• i sat down for a minute to rest


• He went abroad to forget


• I'm going to Austria to learn German

In a more formal style, we often use in order to or so as to.

• He got up early in order to have time to pack.


• I moved to a new flat so as to be near my work.

In negative sentences, we nearly always use the structure with so as not to or in order not to.

• I'm going to leave now, so as not to be late.
  (NOT I'm going to leave now, not to be late.)

infinitive without to

We usually put to before the infinitive (for example i want to go; It's nice to see you).
But we use the infinitive without to in the following cases:

1 Modal auxiliary verbs

After the modal auxiliary verbs will, shall, would, should, can, could, may, might and must, and after had better, we use the infinitive without to.

• I must go now.


• Will you help me?
  


• It might rain


• You had better stop.

2 let, make, hear etc

After some verbs, we use an object and the infinitive without to.
The most common of these verbs are let, make, see, hear, feel, watch, and notice.

verb + object + infinitive without to

• She lets her children do what they want to.
  


• I made them give me the money back.


• I didn't see you come in


• I heard her say that she was tired.

In an informal style, we often use help with this structure.

• Could you help me push the car?

3 why (not)

We can use an infinitive without to after why.
This usually means that it is unnecessary or stupid to do something.

• Why pay more at other shops? Our prices are the lowest.

Why not . . . ?is used to make suggestions.

• Why not ask Susan to help you?

4   and, or, except, but, than

We can join two infinitives with and, or, except, but, or than. The second infinitive is usually without to.

• I'd like to lie down and go to sleep.


• Do you want to eat now or wait till later?


• We had nothing to do except look at the garden.


• I'll do anything but work on a farm.


• It's easier to do it yourself than explain to somebody else how to do it.