This passivized verb form is boiled is infelicitous if it describes the natural process of water boiling.
The fact that the reflexive cannot be passivized lends further support to the claim that it is not a real object.
The verb could be finite or non-finite, but it had to be intransitive (thereby eliminating transitive clauses with object gaps) or a passivized transitive.
Both languages allow the impersonalization of a passivized transitive (but not of a passivized intransitive, since they disallow the impersonalization of non-transitives in general).
A passivized predicate may then be subjectless if it contains no terms, or none that satisfy the conditions imposed on subjects at large.
The scarcity of such data, and the fact that most passivized unaccusatives have stative meanings or denote events that do not have an identifiable causer, considerably weakens the hypothesis.
V must be intransitive or passivized transitive.
Besides the above, unergative verbs differ from unaccusative verbs in the fact that, in some languages, they can be passivized to a limited extent.
