You look just as bad as he does.
I think we want it more than they do.
be as a main verb
10.64 However, the linking verb be is repeated, in an appropriate form. For example, I was scared and the children were too.
‘I think you’re right.’ – ‘I’m sure I am.’
If the second verb phrase contains a modal, you usually put be after the modal.
‘I’m from Glasgow.’ – ‘I thought you might be.’ ‘He thought that it was hereditary in his case.’ – ‘Well, it might be.’
However, this is not necessary if the first verb phrase also contains a modal.
I’ll be back as soon as I can.
Be is sometimes used after a modal in the second clause to contrast with another linking verb such as seem, look, or sound.
‘It looks like tea to me.’ – ‘Yes, it could be.’
have as a main verb
10.65 If the first verb is the main verb have, a form of have is sometimes used instead of a form of do.
She probably has a temperature–she certainly looks as if she has.
leaving words out with not
10.66 You can make the second verb phrase negative by adding not to the auxiliary. These combinations are contracted in informal speech and writing to don’t, hasn’t, isn’t, mustn’t, and so on (see paragraph 5.59 for a list of these contractions). You use the same forms for a negative response to a question.
Some managed to vote but most of them didn’t.
‘You’re staying here!’ – ‘But Gertrude, I can’t, I mustn’t!’
‘And did it work?’ – ‘No, I’m afraid it didn’t.’
Widows receive state benefit; widowers do not.
He could have listened to the radio. He did not.
10.67 With passives, be is often, but not always, kept after a modal.
He argued that if tissues could be marketed, then anything could be.
However, with perfect passives, you can just use the auxiliary have or has. For example, you could say, Have you been interviewed yet? I have.
Note that when a modal with have is used for a passive or progressive verb phrase, been cannot be omitted.
I’m sure it was repeated in the media. It must have been.
She was not doing her homework as she should have been.
10.68 If the second verb phrase contains the auxiliary have in any form, speakers of British English sometimes add done to the group. For example, instead of saying He says he didn’t see it but he must have, they sometimes say He says he didn’t see it but he must have done.
He hadn’t kept a backup, but he should have done.
He hadn’t kept a backup, but he should have.
It would have been nice to have won, and I might have done if I had tried harder.
Similarly, British speakers sometimes use do after modals.
He responded almost as a student might do.
Note that when the verb used in the first mention of an action or state is the main verb have, instead of using do after a modal in the second mention, you often use have instead.
‘Do you think that academics have an understanding of the real world?’ – ‘No, and I don’t think they should have.’
10.69 Usually, the clause with words omitted comes after a clause in which the action or state has been mentioned in full with a main verb. Occasionally, however, for a deliberate effect, it comes before the clause that mentions the action or state in full.
The problems in the economy are now being reflected, as they should be, in the housing market
repeating the main verb
10.70 If you want to be emphatic, you repeat the main verb, instead of leaving it out.
It was the largest swarm of wasps that had ever been seen or that ever would be seen.
contrasting objects and adverbials
10.71 Note that if you want to contrast two different things affected by an action, or two different factors or circumstances, you can put a new object or adverbial in the second clause, with an auxiliary or form of be.
Cook nettles exactly as you would spinach.
You don’t get as much bickering on a farm as you do in most jobs.
Survival rates for cancer are twice as high in America as they are in Britain.
No one liked being young then as they do now.
However, the main verb is sometimes repeated.
Can’t you at least treat me the way you treat regular clients?
10.72 You can omit a verb after the semi-modals dare and need, but only when they are used in the negative.
‘I don’t mind telling you what I know.’ – ‘You needn’t. I’m not asking you for it.’ ‘You must tell her the truth.’ – ‘But, Neill, I daren’t.’
Similarly, the verb is only omitted after the modal expressions had rather and would rather when they are used in the negative. However, the verb is sometimes omitted after had better even when it is used affirmatively.
‘Will she be happy there?’ – ‘She’d better.’
It’s just that I’d rather not.
10.73 You can also leave words out of to-infinitive clauses. Instead of using a full to-infinitive clause after a verb, you can just use to, if the action or state has already been mentioned.
Don’t tell me if you don’t want to.
At last he agreed to do what I asked him to.