French language Q&A Forum

How do you know if a word requires avoir or être in passé composé like for eg finir how do we know if it requires avoir or être when you see the word 

When using avoir as the auxilliary verb in the passe compose, I thought that the past participle had to agree with the direct object... so in the previous exercise there was:

"Nous avons nouri nos chiens" ...are not les chiens the direct object of the verb in that sentence?

"il a fini ses devoirs" ...are not les devoirs the direct object of that sentence...?

...I guess I have got something very wrong here... grateful for any guidance...

Michael 

When using avoir as the auxilliary verb in the passe compose, I thought that the past participle had to agree with the direct object... so in the previous exercise there was:

"Nous avons nouri nos chiens" ...are not les chiens the direct object of the verb in that sentence?

"il a fini ses devoirs" ...are not les devoirs the direct object of that sentence...?

...I guess I have got something very wrong here... grateful for any guidance...

Michael 

Ex. from above:  Ils ont réussi à la convaincre.  Subject They/verb succeeded - requires preposition à before infinitive verb convaincre to convince?

  I am wondering why "la" direct object is used here instead of "lui" please?  Merci!