Who stole my bike? I don't know who stole my bike. It's missing. Who - quien. Quien es, que tomo mi bicicleta? (olvide la palabra que hace los ladrones). Whom did you give the gift to? / To whom did you give the gift - a quien tu dio el regalo? De quien(es)? De quien es esta bicicleta? Whose bike is this? Is it your bike or someone else's? O quisieras leer: Quien digan la gente yo soy? Who do the people say I am? Y tu, Pedro, quienes dices tu, quien soy yo? And you Peter, whom do you say I am. Very often native English speakers don't understand "whom" and just use "who" and 'whose'. I.e. Who is this gift for/ Whom is this gift for?

https://www.ecenglish.com/learnenglish/lessons/who-whom-whose Have a look, but do read more to be sure it's correct.