Grammatica - loco

11
Verbs
222
11.8.2
Perfect tenses of modal verbs
The past participle of modal verbs is not often used. Because of the auxiliary
functions of modals, a perfect tense (including the pluperfect, future perfect
and conditional perfect) is usually followed by another infinitive and in
this case the so-called ‘double infinitive rule’ applies, i.e. if one has an
English sentence where the past participle of a modal verb is followed by
an infinitive, Dutch does not use the past participle but the infinitive of
the modal concerned (see also 11.9.2.5 (a)):
Ik heb hem niet kunnen bezoeken.
I have not been able to visit him.
Ze hadden mogen gaan.
They had been allowed to go.
Zij zal het hebben moeten uitgeven.
She will have had to spend it.
Only when the infinitive for which the modal is acting as auxiliary is not
mentioned (but simply implied) is the past participle used; note the
obligatory use of het in such cases:
Ik heb het niet gekund. I have not been able to (see him).
Zij hadden het gemogen. They had been allowed to (go).
Zij zal het hebben gemoeten. She will have had to (spend it).
The following is commonly done by Dutch people with the perfect tense
of modals: modals all take hebben as their auxiliary verb in the perfect
tense but the speaker is often misled by the infinitive that follows the
perfect of the modal:
Hij is niet kunnen komen. He hasn’t been able to come.
Here the speaker anticipates the verb of motion which follows the modal
and which requires zijn in its perfect tense, but in actual fact it is the
perfect of kunnen which is required here and kunnen requires hebben,
e.g. Hij heeft niet kunnen komen. Similarly Hij is weggemoeten, which is
an abbreviated form of Hij heeft moeten weggaan where gaan is not
mentioned but simply implied (see also 11.8.4).