Unaccusative

The light-verb analysis sketched here also offers us a way of accounting for the fact that in Early Modern English, the perfect auxiliary used with unaccusative verbs was be (as we saw in §7.6), whereas that used with transitive and unergative verbs was have.

We have seen that Unergatives and Unaccusatives differ in 1) permitting the derivation of an Impersonal Passive, and 2) in licensing purpose clauses, since Unergatives have active subjects, and Unaccusatives do not.