When a verb phrase consists of the auxiliary verb do or any of the modal auxiliaries and a lexical verb, the lexical verb takes the form of an infinitive.
- I did tell her.
- Unfortunately, she couldn’t be here tonight.
- Shall I pour the coffee?
- Could you help us?
- They might not come after all.
- You shouldn’t gobble your food like that.
Infinitives of lexical verbs can also be found following other lexical verbs.
- She wants to go to the zoo as her birthday treat.
- Did you remember to buy some new shoes?
- I will try to come to your wedding but I can’t promise to be there.
- I did intend to tell you the whole story one day.
- I was asked to tell her to be ready at twelve o’clock.
Notice that when an infinitive follows a lexical verb, it must be preceded by the word to, whereas when it follows an auxiliary verb, there is no to: lexical verbs are followed by to-infinitives: auxiliary verbs are followed by bare infinitives (that is, infinitives without to).
Bare infinitives are generally found after the primary auxiliary verb do and the modal auxiliaries, but the lexical verb let is also always followed by a bare infinitive:
- Let me help you.
- Let John go instead of you
- Let’s have a cup of tea.
The verb help can be followed by either a to-lnfinltlve ora bare Infinitive:
- Could you help us to put up the tent? OR
- Could you help us put up the tent?
- Will someone help us to cany our luggage? OR
- Will someone help us carry our luggage?
The idiomatic expression can’t help (= ‘be unable to prevent something or stop oneself doing something’) is followed by a verbal noun:
- I can’t help laughing at what happened.
- I can’t help you falling In love with the wrong person.
The expression can’t help but (= ‘be unable not to do something’) is followed by a bare infinitive:
- You can’t help but admire her courage. (= you have to admire her courage)
То-infinitives can be found not only after lexical verbs but also after adjectives, nouns and wh-words such as who and where.
- I am very pleased to meet you at long last. (after adjective)
- We were sorry to hear of her sudden death. (after adjective)
- I have no desire to live in France. (after noun)
- We hadn’t the courage to tell her the truth. (after noun)
- He hasn’t got the intelligence to invent a story like that. (after noun)
- I haven’t a clue where to find him. (after wh-word)
- I don’t know how to get there from here, nor who to ask for directions. (after wh-word)
To-infinitives can also be used in other constructions.
As the subject or complement of a verb:
- To break the vase was bad enough; to lie about it was worse.
- My greatest wish is to find true happiness.
- To know her is to love her.
After for + a noun or pronoun:
- For me to meet her would be a great honour.
- It won’t be easy for us to get in.
- It wasn’t a very good idea for her to tell him what she thought.
To express purpose:
- We’ll need some paper to wrap the books in.
- I’ve brought a bag to carry the shopping in.
In comment clauses:
- To be honest with you, I don’t much like the idea.
- To tell you the truth, I never liked her anyway.
Present infinitives and past infinitives
Present infinitives are the simple infinitives of lexical verbs:
- She must go.
- She wants to go.
- We should leave at once.
- It is time for us to leave.
Past infinitives or perfect infinitives are formed from the infinitive of the auxiliary verb have plus the past participles of lexical verbs:
- She must have gone by now.
- She hopes to have left before then.
- We should have left earlier.
When some parts of a sentence are left unsaid because they can be understood from what has been said before, the word to may be all that represents a to-infinitive and anything that might have followed it:
- Come here when I tell you to. (= … when I tell you to come here)
- ‘Why are you painting that?’
- ‘Because I want to’. (= … because I want to paint it)
- ‘Do your parents live here?’
- ‘No, but they would like to.’
- I don’t want to argue with her but I may be forced to.
The Split Infinitive
When the two parts of a to-infinitive are separated by one or more words, such as an adverb or adverbial phrase, this is known as a split infinitive:
- It may be difficult to properly clean the oil off the car.
- I would like to completely and utterly deny that I had any part in their evil scheme.
- Their mission was to boldly go where no-one had ever gone before.
Although there have been split infinitives in English since at least the 14th century, and although they are to be found in the works of some of the best writers in the English language, the split infinitive has often been condemned as ‘ungrammatical’, especially by school-teachers, and is still felt by many people today to be incorrect (probably because that is what they were taught in school!).
Split infinitives are not ungrammatical. However, since there are many people who think that they are ungrammatical, or at least that they are something to avoid in careful writing, it may be better, in order to avoid criticism, not to use them if it is possible not to. The following brief rules could be taken as a guide to good practice:
- If the verb is intransitive (that is, it has no object), put the adverb after it:
- We will need to plan carefully for our holidays.
- If the verb is transitive, it is generally better to put the adverb after the object if the object is quite short:
- We will need to plan our holiday carefully.
- However, adverbs such as really, strongly, fully, thoroughly that emphasize the action of the verb are often better placed splitting the infinitive:
- You don’t need to drink alcohol to really enjoy yourself.
- To fully understand what has happened here, we need to look at the recent history of the country.
- If the object of a transitive verb is a fairly long-phrase or a clause, it is often better to put the adverb either immediately after or else in front of the verb. If instead of an adverb there is an adverbial phrase, it may be best placed after the object phrase or clause. It is difficult to give an absolute rule for this – often it is simply a matter of what sounds best:
- We will need to plan carefully what we are going to do next.
- We will need to carefully plan what we are going to do next.
- We will need to plan what we are going to do next very carefully.
- While putting the adverb between to and the verb was once considered incorrect, it is nowadays generally acceptable.
- Only in very formal English should you put the adverb in front of to:
- I was not perceptive enough fully to appreciate his massive achievement.
- To many people nowadays, this sounds very stilted and unnatural, and it would not be normal in informal English. It is, however, better to put the negative adverb not before to: ‘not to go’ is definitely better than ‘to not go’:
- To be or not to be, that is the question. [William Shakespeare]
- This is a good example of how not to do the job.
- Not to turn up at her party would be a bit insulting, don’t you think?
- The same is true for never.
- ’Tis (= It is) better to have loved and lost,
- Than never to have loved at all. [Alfred, Lord Tennyson]
- There are some constructions in English that absolutely require a split infinitive, for example, more than:
- He has worked hard enough to more than make up for the time he was off school through illness.
- Sometimes it is better to use a split infinitive in order to make the meaning of a sentence absolutely clear. Look at this sentence:
- My job is really to understand the needs of the staff.
It is not clear exactly what the sentence means. It could mean that my job is ‘really understanding’ the needs of the staff, but it could also mean that what my job ‘really is’ involves understanding the needs of the staff. Because of the position of the adverb, it is not clear which of the two verbs it is modifying, is or understand. However, with a split infinitive, as in
- My Job is to realty understand the needs of the staff.
the adverb really must refer to the verb understand. Splitting the infinitive makes the meaning of the sentence clearer.