We just learned that in Italian I am happy is sono felice.
Now let's learn how to say You are sad.
Sei triste
We can break it up into two words:
You are - Sei - sounds like say-ee /?/
sad - triste - Sounds like t-dee-stay /?/
So all together Sei trista sounds like say-ee t-dee-stay.
(from: wikipedia - accademia della crusca)
In German:
Sie sind traurig
In Spanish:
Estas triste
In French:
Vous êtes triste