Editing Auxiliary verb (section)

==Light verbs==
Some syntacticians distinguish between auxiliary verbs and [[light verb]]s.<ref>Concerning light verbs in English, see Allterton (2006:176).</ref><ref>Light verbs are called ''Funktionsverben'' 'function verbs' in German – see Engel (1994:105f.) and Eroms (2000:162ff.).</ref> The two are similar insofar as both verb types contribute mainly just functional information to the clauses in which they appear. Hence both do not qualify as separate [[Predicate (grammar)|predicate]]s, but rather they form part of a predicate with another expression – usually with a full verb in the case of auxiliary verbs and usually with a noun in the case of light verbs.

In English, light verbs differ from auxiliary verbs in that they cannot undergo inversion and they cannot take ''not'' as a postdependent. The verbs ''have'' and ''do'' can function as auxiliary verbs or as light verbs (or as full verbs). When they are light verbs, they fail the inversion and negation diagnostics for auxiliaries, e.g.

Note that in some dialects (for example, the West and South West dialects of [[Hiberno-English]]), the inversion test may sound correct to native speakers.
 
::a. They '''had''' a long meeting.
 
::b. *'''Had''' they a long meeting? <small>- Light verb ''had'' fails the inversion test.</small>

::c. *They '''had''' not a long meeting. <small>- Light verb ''had'' fails the negation test.</small>

::a. She '''did''' a report on pandering politicians.
 
::b. *'''Did''' she a report on pandering politicians? <small>- Light verb ''did'' fails the inversion test.</small>
 
::c. *She '''did''' not a report on pandering politicians. <small>- Light verb ''did'' fails the negation test.</small>

(In some cases, though, ''have'' may undergo auxiliary-type inversion and negation even when it is not used as an auxiliary verb – see {{slink|Subject–auxiliary inversion|Inversion with other types of verb}}.)
 
Sometimes the distinction between auxiliary verbs and light verbs is overlooked or confused. Certain verbs (e.g., ''used to'', ''have to'', etc.) may be judged as light verbs by some authors, but as auxiliaries by others.<ref>Jurafsky and Martin (2000:22), for instance, lists ''have'' as a modal auxiliary when it appears as ''have to'' and Fowler's Modern English Usage (1996:195) lists ''used to'' as a "marginal modal".<!--[Dubious: these sentences would be OK in some lects] These verbs do not qualify as modal auxiliaries based upon the inversion and negation diagnostics, e.g., ''*Has Fred to help?'', ''*Fred has not to help'', ''*Used Fred to help?'', ''*Fred used not to help''.--></ref>