in his room
Joven amo, ¿habrá visto gente diminuta en su cuarto?
Young master, have you seen tiny people in your room?
— Arrietty y el mundo de los diminutos (2010)
Está en su cuarto y no quiere salir.
She's in her room and doesn't want to come out.
— Porco Rosso (1992)
Tom se encerró en su cuarto.
Tom locked himself in his room.
I heard her singing in her room.
Hay muchos libros en su cuarto.
There are many books in his room.
Está poniendo en orden las cosas en su cuarto.
She's tidying up her room.
Tom comía todas sus comidas en su cuarto.
Tom ate all his meals in his room.
Si no fuera por él, Neil estaría en su cuarto, estudiando química.
If it weren't for him, Neil would be in his room, studying chemistry.
— El club de los poetas muertos (1989)