English auxiliaries and contractions

In English grammar, certain verb forms are classified as auxiliary verbs. Exact definitions of this term vary; an auxiliary verb is generally conceived as one with little semantic meaning of its own, which modifies the meaning of another verb with which it co-occurs. In English, verbs are often classed as auxiliaries on the basis of certain grammatical properties, particularly as regards their syntax – primarily whether they participate in subject–auxiliary inversion, and can be negated by the simple addition of not after them.

Certain auxiliaries have contracted forms, such as 'd and 'll for had/would and will/shall. There are also many contractions formed from the negations of auxiliary verbs, ending in n't (a reduced form of not). These latter contractions can participate in inversion as a unit (as in Why haven't you done it?, where the uncontracted form would be Why have you not done it?), and thus in a certain sense can be regarded as auxiliary verbs in their own right.

For details about the verbs classed as modal auxiliaries, see English modal verbs.

An auxiliary verb is most generally understood as a verb that "helps" another verb by adding grammatical information to it. On this basis, the auxiliary verbs of English may be taken to include:

The following are examples of sentences containing the above types of auxiliary verbs:

However the above understanding of auxiliary verbs is not always strictly adhered to in the literature, particularly in the case of forms of the verb be, which may be called auxiliaries even when they do not accompany another verb. Other approaches to defining auxiliary verbs are described in the following sections.

There is a group of English verbs which have certain special grammatical (syntactic) properties that distinguish them from other verbs. This group consists mainly of verbs that are auxiliaries in the above sense – verbs that add grammatical meaning to other verbs – and thus some authors use the term "auxiliary verb", in relation to English, to denote precisely the verbs in this group. However, not all enumerations of English auxiliary verbs correspond exactly to the group of verbs having these grammatical properties. This group of verbs may also be referred to by other names, such as "special verbs".

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