A construction-based analysis of the English modal be to

This article presents a construction-based analysis of the English modal be to, as in John is to stay in town. Drawing on standard and novel arguments and evidence, it is argued that sentences with the be to are not bi-clauses but mono-clauses. It is also contended that the combination is a semantic and grammatical unit whose parts are syntactically separable. While the be part undergoes various grammatical operations, the whole unit denotes a deontic modality such as necessity. The article proposes an analysis of the unit as a construction that is stored in the lexicon and is combined with a main verb phrase at phrasal syntax. It also addresses a couple of advantages over previous accounts.