Why is there an 's' on lu?

Question

In statement: il les a tous lus (he has read all of them) why is there an s on lus? It is: il a lu so I presume it's got something to do with tous but I'd like an explanation if possible.

Answer

les is a direct object and when it comes before the verb in the passé composé the veb agrees. Thus:
Il a lu les livres (no agreement)
Les livres, il a tous lus. (direct object - les livres before the verb)

Answer

Clear. Thanks.

Answer

Bonjour Renate !

Here is a link to our lesson on that special agreement rule:
https://french.kwiziq.com/revision/grammar/special-cases-when-the-past-participle-agrees-in-number-and-gender-when-used-with-avoir-in-le-passe-compose-conversational-past

À bientôt !

Answer

Helpful. Thanks