No subject

[bogus at does.not.exist.com]

out." to such things as counterfactual conditionals. "He went."-->"Had
he gone..." or "If he had gone...", including different patterns for
the formal, even the old-fashioned (to prepare students for
literature) and the more colloquial. Or dialect. "If'n he went...", if
a student so chooses.

A quite decent summary of some of the development of this field is in