auxiliary verbs

1 the need for auxiliary verbs
In English sentences, a lot of important meanings are expressed by the verb phrase – for example questioning, negation, time, completion, continuation, repetition, willingness, possibility, obligation. But English verbs do not have many different forms: the maximum (except for be) is five (e.g. see, sees, seeing, saw, seen). So to express all these meanings, ‘auxiliary’ (or ‘helping’) verbs are added to other verbs. There are two groups.
2 be, do and have
Be is added to other verbs to make progressive and passive forms.
Is it raining? She was imprisoned for three years.
Do
is used to make questions, negatives and emphatic forms of non-auxiliary verbs.
Do you smoke? It didn’t matter. Do come in.
Have
is used to make perfect forms.
What have you done? I realised that I hadn’t turned the lights off.
See the Index for details of entries on these forms and their uses, and on non-auxiliary uses of be, do and have.
3 modal auxiliary verbs
The verbs will, shall, would, should, can, could, may, might, must and ought are usually called ‘modal auxiliary verbs’. They are used with other verbs to add various meanings, mostly to do with certainty or obligation.
She may be on holiday.
You must write to Uncle Arthur.
For details, see modal auxiliary verbs: introduction-354 and the entries for each verb.
4 other verb + verb structures
Other verbs (e.g. seem) which are used in verb + verb structures are not usually called ‘auxiliary verbs’. One important difference is grammatical. In auxiliary verb structures, questions and negatives are made without do-, in other verb + verb structures the auxiliary do has to be added to the first verb. Compare:
– She ought to understand. – He is swimming.
Ought she to understand? He is not swimming
– She seems to understand. – He likes swimming.
Does she seem to understand? He doesn’t like swimming.
auxiliary verbs
• see auxiliary verbs
• dropping words after auxiliaries see ellipsis 5: after auxiliary verbs
• stressed for emphasis see emphasis.2