Questions about the Passé Composé
Q: Why is it j'ai aimé and NOT j'ai aimer?
The passé composé is formed with the present of avoir, followed by a past participle (not the infinitive).
Q: Why is it il a su and NOT il a savé?
The verb savoir has an irregular past participle (su).
Q: Why is it Elle a vu and NOT Elle a vue?
One does not make agreement with a subject when the auxiliary verb is avoir.
Q: Why is it Les livres que j'ai lus and NOT Les livres que j'ai lu?
Since livres is a plural direct object (it answers the question "what?") that precedes the verb, the past participle must show plural agreement.
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