Semi-Auxiliaries

Under the category of semi-auxiliaries, we have placed several verbs that do not seem to closely follow the behavior of auxiliaries. One of these auxiliaries, dare, mainly behaves as a modal and selects for the base form of the verb. The other semi-auxiliaries all select for the infinitival form of the verb. Examples of this second type of semi-auxiliary are used to, ought to, get to, have to, and BE to.