[...] dependent clauses are shown to be so by the verb, or by the absence of any verb (or the presence of the particle ‘as’) instead of the verb ‘be’. Thus ‘John is there’ is indipendent, but ‘John be there’, J’ohn were there’ (both often used in formal discourse after ‘if’), ‘John being there’, ‘John to be there’, ‘John there’ are dependent. [...] Each variety of dependent clause has its own range of use.
- Hockett (1958), a pag.206