He hides his sorrow behind a smile.
 - Il cache sa tristesse derrière un sourire.
He was attracted by her smile.
 - Il était attiré par son sourire.
The man grinned widely and stood up. He then paid the bill and emptied his glass of beer in one gulp.
 - L'homme fit un large sourire et se leva. Il paya alors l'addition et vida sa bière d'une seule gorgée.
He grinned with delight.
 - Il fit un large sourire de satisfaction.
I saw a joyful smile on his face.
 - Sur son visage, je vis un joyeux sourire.
She always talks with a smile on her lips.
 - Elle parle toujours le sourire aux lèvres.