Leaving out words after auxiliary verbs – Rules and exercises for advanced level

Leaving out words after an auxiliary verb allows us to avoid repeating whole verb groups from previous sentences.

Study these examples:

1. The birds are singing again. They are always singing.

2. The birds are singing again. They always are.

We use the auxiliary verb 'are' (to be) with 'singing' in the sentence group below but in example 1 the second sentence is too long and cumbersome. In example 2 the auxiliary verb 'are' remains in the second sentence but the second verb 'singing' has been removed leaving the sentence group more concise.

We have the grammar rules and a few exercises for you.

Leaving words out after auxiliary verbs: Explanation and use

In a longer expression, instead of repeating two verbs, we might use an auxiliary verb on its own in the second sentence or phrase.

1. Where 2 auxiliary verbs are used, the shortened form can use either the first or both in the second sentence

Cinderella hadn't been invited to the ball, but her ugly sisters had been invited to the ball.

Becomes the more concise

Cinderella hadn't been invited to the ball, but her ugly sisters had.

OR

Cinderella hadn't been invited to the ball, but her ugly sisters had been.

2. Where there is no auxiliary verb in the first sentence or there is a form of the auxiliary do, 'to do' is used as the auxiliary verb for the second sentence

'I now run faster than he does.' 'Of course you run faster than he does.'

Becomes the more concise

'I now run faster than he does.' 'Of course you do.'

3. Where 'have' is the auxiliary verb in the first sentence, either 'to have' or 'to do' are used as the auxiliary verb in the second sentence

'Do you think she has a chance of coming first?' 'Yes I do think she has a chance of coming first.'

Could become either of these more concise versions

'Do you think she has a chance of coming first?' 'Yes I do.'

OR

'Do you think she has a chance of coming first?' 'Yes she has.'

4. Where the verb to be is the main verb in the previous sentence, we repeat a form of the verb be in the second sentence

I am not walking up the mountain, but my brother is walking up the mountain.

Becomes the more concise

I am not walking up the mountain, but my brother is.

5. Where the verb to be is the auxiliary verb in the previous sentence, we can use a modal verb with or without be and the second sentence is shortened to either of the two examples below.

Is Ella staying for dinner? Yes I think she is staying for dinner.

Here

Is Ella staying for dinner? Yes I think she will.

OR

Is Ella staying for dinner? Yes I think she will be.

6. Where the verb to be is the main verb or the auxiliary verb within a passive in the previous sentence, we use a modal with be (which can't be left out).

The book was delivered within a week. The shop said it would be delivered within a week.

becomes

The book was delivered within a week. The shop said it would be.

7. Where have is the auxiliary verb, we can follow the auxiliary verb 'have' by 'done' in the second sentence.

She has never made a mistake before. Well, she has made a mistake this time.

becomes

She has never made a mistake before. Well, she has (done) this time.

8. Where a modal auxiliary verb (can, could, may, might, must, ought to, shall, should, will, would) is the auxiliary verb, we can use do (particularly in spoken English).

Will you see Tony tonight? I might see Tony tonight.

becomes

Will you see Tony tonight? I might (do).

Here is a table to help you master these rules: