Substitution and Omission: Leaving out Words After Auxiliaries

An auxiliary verb (be, have, can, will, would, etc.) can be used instead of a whole verb group or instead of a verb in order to avoid repeating words from a previous clause.

They say they have already chosen a candidate for the job but I don’t think they have.

- Would any of you be happy to live alone? - I would.

If the auxiliary verb in the previous clause or sentence is complex, then we can leave out everything except for the first auxiliary verb:

- They could have been stuck in traffic. - Yes, they could.

If there is no auxiliary verb in the previous clause or sentence, or if the auxiliary is a form of do, we can use a form of do instead of repeating the main verb. We use do when the main verb is used in present simple form and did when it is a past simple form:

Laura goes to the gym twice a week, and I do too.

- I didn’t tell anyone about it! - Relax, no one thinks you did.

If be is the main verb in the previous clause or sentence, we must repeat it:

- Your brothers are so noisy. - Yes, they always are.

If have or have got is the main verb in the previous clause or sentence, we can usually use a form of either do or have:

- Do you think I have any chances to get this job? - I bet you have. (or I bet you do.)

However, if we use have + noun in the previous clause or sentence to talk about actions (have a shower, have a shave, have a good time, etc.) we prefer do:

I was sure I wouldn’t be able to have a good time, but I did.

If we use have as an auxiliary verb, we can often follow it with done instead of repeating the main verb. This happens particularly in spoken English:

- She has never said anything bad about me. - In fact, she has (done) this time.

However, this is usually not possible when the verb being substituted is intransitive:

- Has he already gone? - I think he has. (not has done)

Similarly, after a modal auxiliary verb (can, could, may, might, must, ought to, shall, should, will, would) we can use do, particularly in spoken English:

- Will you be seeing them today? - I might (do).

Sometimes we can use be instead of do with a similar meaning:

- Will you be seeing them today? - I might do / be. ( “do” replaces “see them today”, “be” replaces “be seeing them today”)

If we use be as an auxiliary verb in the previous clause or sentence, we can use be after a modal:

- Is Tom staying the night? - No, I think he won’t (be).

However, if be is used as a main verb in the previous clause or sentence, or as an auxiliary verb within a passive structure, we can usually leave out be after a modal in informal contexts only.

- Jackson is going to be late. - I knew he might (be). (informal)

Leaving out to-infinitives

“To” is sometimes used instead of a clause beginning with a to-infinitive when it is clear from the context what we are talking about:

I wish I could visit you, but I won’t be able to.

It might have been a better idea to give her kids more freedom but she chose not to.

However, when we use the verb be in the previous sentence or clause the to-infinitive form of be is repeated in the next clause or sentence:

Jessica was absolutely furious - I never thought she could be.

After most nouns and adjectives that can be followed by a to-infinitive clause, we can leave out the to-infinitive clause or use to:

plan, chance, idea, opportunity, promise, suggestion; afraid, delighted, determined, willing

I’m not going to move from this apartment. At least, I don't have any plans (to).

- Will you be able to make it up with him? - Well, I’m determined (to).

We can also leave out a to-infinitive or use to with some verbs:

to promise, to forget, to agree, to ask, to begin, to refuse, to start, to try

- Why didn’t Richard visit the theatre with us? - He refused (to).

- Will Lizzy pick me up? - Yes, she promised (to).

We don’t leave out to after verbs which can’t be used without a complement:

to mean, to advise, to afford, to be able, to choose, to deserve, to expect, to fail, to hate, to hope, to intend, to love, to need, to prefer

- Will you go to Malta next year? - I hope to.

I admit that I offended you but I didn’t mean to.

After want and would like in if-clauses and wh-clauses, we can either leave out a to-infinitive or use to:

You can have another piece of cake if you’d like (to).

Take a seat if you want (to).

You can come whenever you want (to).

In other clauses (not if- and wh-clauses), we include to:

I was planning to spend an evening together with her, and I would still like to.

I was there because I wanted to, not because someone forced me to be there.

In if-clauses and wh-clauses, we usually leave out to after like:

- These cupcakes look so delicious! - You can have one if you like.

You can leave whenever you like.

NB! We include to with negative forms of want, would like, and like, including in if-clauses and wh-clauses:

- Shall we go for a walk? - I don’t really want to.

I should have told you before but that would have made you upset so I didn’t want to.

She wouldn’t mind you asking for help. - No no, I wouldn’t like to. I’ll manage.