To conjugate verbs in the passato prossimo (and other compound tenses) where a modal verb is needed the following formation is required:
AUXILIARY VERB (avere or essere) + MODAL VERB (past participle form) + INFINITIVE
The rule for determining which auxiliary verb to use is determined by the infinitive (as opposed to the modal verb) Take for example the following:
Ho potuto comprare un biglietto (I was able to buy a ticket)
as well as:
Sono potuto andare al cinema (I was able to go to the movies)
The difficulty arises when looking at reflexive verbs that universally require essere as an auxiliary verb. For example:
Mi sono svegliato alle 6.00 di mattina. (I woke up at 6 in the morning.)
When you add a modal verb to this structure, how is it correctly rendered?
- Ho dovuto svegliarmi
- Sono dovuto svegliarmi
If the first example is correct, why does it not follow the rule that the auxiliary verb is determined by the infinitive 'svegliarmi' as it normally is?