Accord avec plusieurs COD de genre différent

This rule applies to the past participle in the passé composé. Usually, when you use the verb avoir, the past participle stays the same. However, if the objects (the things you are talking about) come before the verb, the participle must agree with them. This happens most often with the word que (that/which) or the pronoun les (them). When these objects are a mix of masculine and feminine, we use the masculine plural form. Think of it like a group of friends. If there are five girls and one boy, in French, they are collectively called ils. The same logic applies to your objects. You are essentially grouping them under a single masculine umbrella. It keeps the sentence structure clean and predictable. Even native speakers have to pause for a second to get this right in writing, so don't worry if it takes a moment to click!

1. 1To master this, follow these three simple steps:
2. 2Identify your direct objects (the things receiving the action).
3. 3Check their genders. If you have at least one masculine and one feminine, treat the group as masculine plural.
4. 4Add an s to the end of your past participle (the masculine plural ending).
5. 5For example, if the objects are le vélo (masculine) and la voiture (feminine), your past participle pris (taken) stays pris (because it already ends in 's') or acheté becomes achetés. You do not add an e for the feminine part. The masculine s is the final word.

You use this rule in very specific scenarios. The most common is when using the relative pronoun que. Imagine you are at a job interview. You want to talk about the report (le rapport) and the presentation (la présentation) that you finished. You would say: "Le rapport et la présentation que j'ai finis." Another scenario is using the pronoun les. If you are talking about your keys (les clés, fem.) and your phone (le téléphone, masc.), and you lost them, you say: "Je les ai perdus." Use this whenever the objects are clearly identified before the verb happens. It shows you are paying attention to the details of the things you are discussing.

Do not use this rule if the objects come after the verb. This is the most common trap for beginners! If you say "I bought the dress and the hat," you say: "J'ai acheté la robe et le chapeau." No s is needed here. Why? Because when you say the verb acheté, you haven't "seen" the objects in the sentence yet. The agreement only happens when the objects have already been mentioned. Also, do not use this if all the objects are feminine. If you bought two dresses, it would be achetées. The masculine rule only kicks in when there is a mix. Think of the masculine gender as a very loud guest at a party—if he's there, everyone follows his lead.

The biggest mistake is trying to be "too fair." You might want to add an e and an s to represent both genders. For example, writing achetées for a mix of a car and a bike. This is incorrect. Another mistake is forgetting the agreement entirely when the objects are before the verb. Many people just write the basic form acheté. While you will still be understood when speaking (since acheté and achetés sound the same), it is a major spelling error in writing. Finally, watch out for nouns that look feminine but are actually masculine, like le problème. If you have a problem and a solution, the masculine plural wins!

How does this differ from other agreements? With the verb être, the verb agrees with the subject (the person doing the action). If a man and a woman go out, we say "Ils sont sortis." This follows the same "masculine wins" logic. The difference with our current rule is that we are looking at the objects, not the people. If a woman buys a book and a pen, the verb agrees with the book and pen (achetés), not with the woman. It is all about what is being acted upon. It is like a grammar traffic light: être looks at the driver, while avoir (with preceding objects) looks at the passengers.