"They express their happiness."

Translation: Ellos expresan su alegría.

[Brycecrab]

Why not felicidad in place of alegría?

[DroppedBass]

Both should be correct. There is a small difference between Alegría and Felicidad, though.
Alegría refers to the emotion that makes you smile, while felicidad is a deeper kind of happiness.

[Brycecrab]

So are you saying alegría indicates mild happiness and felicidad indicates great happiness?

[LaisaLin]

sort of, but also, alegría tends to be a short-lived feeling, while felicidad is supposed to be a deeper, longer lasting state of being

[JenniferSu318351]

I wonder the same

[Bruce768614]

Duo accepts felicidad--9/29/2018.

[Bruce768614]

Duo just reneged and refused that same answer --4/12/2020.

[Bruce768614]

BUT they accept it without "Ellos"--just "Expresan su felicidad."

[Mack48383]

Why not sus? As ellos is plural.

[LaisaLin]

because felicidad is singular, and that's what su refers to

[GatitaRoja]

They even suggest felicidad, yet marked it wrong. Reported.

[pia.damsgaard]

Maby something else was wrong because filicidad is accepted

[Antonpanton]

Why is "ellos se expresan su felicidad" marked wrong... thought the verb was "expresarse".

[Elhombredeviajes]

Ha! Alegría!