about de past tense

Is there an special rule to use the verbs ETRE AND AVOIR, as auxiliars, with other verbs, ? for example, can i use etre with finir, o aimer with etre? Because in the lesson 3.7 and 3.8 ALLEr used as auxiliar ETRE, is posible using AVOIR? Thanks

I think what you're getting into is in the realm of using subjunctive (mood) and imperfect tenses so, no, *être* is not interchangeable with *avoir* because you would be using a completely different conjugation and a different tense.

The auxilliaries être and avoir are used with the passé compose, plus-que-parfait, and subjonctif passé, three of the past tenses. They are also used with the mood conditionnel passé. The auxilliary être or avoir is used before the verb being conjugated, and most of the time avoir is the auxillary used. The verb auxillary être is used with intransitive verbs such as aller, mourir, entrer, venir and sortir. No, être and avoir aren't interchangeable; hovever, there just could be a rule-breaker (I'm unaware of if there are any.) Of the verbs Jose listed, finir and aimer are transitive verbs, that means they take direct objects. Finir: in English we would say "I finished the race." Aimer: In English we would say "I love John." The verbs finir and aimer must have direct objects, or recipients, of the action. Aller, on the other hand is intransitive; it just states action; in English we would simply say "I go." This verb can't act upon anything, therefore, it has no direct object. Because French verbs are considerably more difficult to conjugate than are the English, a good guide to conjugating verbs is a valuable purchase. I have Bescherelle; when I bought it in 2012, it cost $21.95 CDN. It's printed in 2 versions, with information on verb usage in either French or in the English language. You may be able to find it on Amazon or ebay.