#bertiebear | yappeur dévoué
1 messages · Page 1 of 1 (latest)
Our volunteers look into many questions every day; sometimes it takes them a little while to answer.
Make it descriptive, including relevant context, but also to the point. This way you improve your chances of getting a more relevant and specific answer.
My instinct would make me write "J'en ai mis une" and not "J'en ai mise une".
Looking at the rules, "en" is an undefined pronoun that means "a part of, a certain number of". Here, it represents one song out of the pool of songs. Grammaticaly, the agreement with "en" is made with the masculine singular form, and not the one of the things it represents.
Here's another example with a feminine plural, fleurs.
- As-tu touché les fleurs ?
- J'en ai touché certaines
And not "J'en ai touchées certaines".
Or this example where the noun is feminine, and also one of its parts ("une part" = "a slice)
- As-tu mangé de la tarte ?
- Oui, j'en ai mangé (une part/une portion)
And not "J'en ai mangée" or "J'en ai mangées".
Etc
The agreement can only be made when en is used with the relative pronoun que.
Ex: "Toutes les leçons que j'en ai tirées m'ont beaucoup servi"
Here que is the COD and the agreement can be made with les leçons.
Right but here, « en » isn't an essential part, right? It's replacing something else
Because the underlying structure is « Toutes les leçons que j'ai tirées [de qqch] »
Whereas with my example, « en » is essential; I can't drop « en » and still have « une »
Yes, if you drop the en you'd have to specify "J'ai mis une chanson/une musique". I was just giving you the case where the agreement can be made when using it. 
ah okay, cheers
Unless of course, if the context is clear within your dialogue, the character could have just said very casually "J'ai mis/lancé une très aiguë" without specifying chanson again.
Note that this is grammatically off, but I've heard people skip it when speaking casually (informal), dropping the en when an adjective is present.
ça m'a l'air faux
oui car ça l'est 😄