I like the way you smile.
- J'aime ta façon de sourire.
He hides his sorrow behind a smile.
- Il cache sa tristesse derrière un sourire.
I don't care if you don't like your Aunt Mary. You'll just have to grin and bear it while she's here.
- Je ne veux pas savoir si tu n'aimes pas ta tante Marie. Tu n'as qu'à juste te forcer à sourire et supporter tant qu'elle est ici.
That person has had an odd grin on his face for a while. What do you suppose is behind it?
- Cette personne a eu un étrange sourire sur la figure pendant un instant. Que pensez-vous que cela cache ?
She approached him with a smile on her face.
- Elle lui fit des avances, un sourire aux lèvres.
I saw a joyful smile on his face.
- Sur son visage, je vis un joyeux sourire.