Questions about Auxiliaries
Q: Why is it je suis allé and NOT j'ai allé?
The verb aller forms its passé composé with être, not with avoir.
Q: Why is it je me suis couché and NOT je m'ai couché?
In addition to verbs like aller, venir, sortir, etc., pronominal verbs (those that are always preceded by a pronoun like me, te, se) also use être when used in the passé composé or some other past tense. The most common of these verbs are se coucher, se promener, se laver, se brosser.
Q: Why is it elle est partie and NOT elle est parti?
When the auxiliary verb is être, the past participle must show agreement with feminine and plural subjects.
Q: Why is it j'ai monté la valise and NOT je suis monté la valise?
The auxiliary être is only used with monter when the subject undergoes the verbal action (here it is the object, valise, that undergoes the action).
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