Quasi-auxiliaries

English contains many verb phrases that function as quasi-auxiliaries, such as be going to, used to, is about to. These quasi-auxiliaries require an infinitive. Others take a gerund (e.g. need, as in need fixing, in American English), past participle (e.g. get, as in get done), or other verb form.

In American English, go and come can be quasi-auxiliaries with nothing between them and the following verb phrases, but only in their plain forms: "Come show me", "I'll go get it", and "I had to come see for myself". This use can be regarded as ellipsis of and — the previous are equivalent to "Come and show me", "I'll go and get it", and "I had to come and see for myself" — and British English requires the and to be included, as does American English when the verb is not in its plain form: "I went and saw him." (It is also possible in both dialects for to to be used in place of and, though this typically has a slightly different sense.)