have + to = should they be analysed together as a semi-modal auxiliary or should they be considered separately, i.e.,
have = primary auxiliary verb
to = preposition or something else ?
Most writers on grammar consider 'have to' to be a semi/quasi- modal (auxiliary)
Do we recognise a modal verb by the fact that it does not take any inflections ?
The core modals do not take inflections, do not use DO in negative and interrogative forms, are followed by a bare infinitive, etc.
In that case "will" would be a modal but not "have to" ??