9) The subject of a personal infinitive
a) is either a noun or a pronoun:
Abri a porta para Pedro entrar.
Abri a porta para eles entrarem.
b) uses the subject form (not the object form) if it is a pronoun;
English uses an object pronoun or a possessive adjective; compare:
by / because of my leaving
10) The subject of a personal infinitive is either explicit or implicit.
a) An explicit subject eliminates ambiguity in the
1st- / 3rd-persons singular
(which share the same form);
(which, like the 3rd-singular, can refer
to an infinite number of subjects):
(before who went? the cat?)
Vi o gato antes de eu ir.
As tias viram os gatos antes de irem.
(before who went? the cats?)
As tias viram os gatos antes de elas irem.
b) It is not necessary to state the subject of a 1st-person plural or a 2nd-person
infinitive, since the endings of these forms reveal their subject.
Vimos o gato antes de sairmos.
(the subject can only be nós)
11) A compound infinitive (either impersonal or personal)
a) is the infinitive ter ("to have") + masculine singular past participle;
1
b) expresses an action or state of being completed before that of the main verb:
É bom elas terem viajado!
(for them to have traveled)
---------------------------------------------------------------------------------------------------------------------
1
haver occasionally replaces ter, although colloquial Portuguese prefers ter.