- Examples: may, can, will, shall, might, could
- English auxiliaries differ from verbs in that they show the following properties, the NICE properties:
A finite auxiliary precedes the negation particle not to negate a sentence.
- Pat will not walk home.
- *Pat walked not home.
A finite auxiliary stands at the beginning of a sentence in yes/no-questions.
- Will Pat walk home?
- Walked Pat home?
There is an idiosyncratic contraction form of the auxiliary and the negation particle.
- won't, can't
An auxiliary can occur in VP ellipsis, i.e. at the end of a sentence when a VP is missing.
- Pat should walk home and Mary might, too.
- *Pat walked home and Mary, too.
- General properties of the modal auxiliaries:
- no inflection for 3rd singular
- only a finite form
- Problematic cases: