Relative pronouns are used to link phrases together.
Que can refer to people or things and means who, that or which. It can be left out in English but is always included in Spanish, eg la chica que vive en la misma calle (the girl who lives in the same street), las asignaturas que prefiero (the subjects which/that I prefer).
Quien and quienes (plural) mean who and can only be used for people, eg mi hermano, quien es abogado, vive en Londres (my brother, who is a lawyer, lives in London), mis profesores, quienes son muy estrictos, siempre gritan (my teachers, who are very strict, always shout).
Lo que is used to mean what (or that which) when you are talking about a general idea, eg lo que no me gusta es el uniforme (what I don't like is the uniform), lo que prefiero es escuchar música (what I prefer is listening to music).
El que, la que, los que and las que refer to both people and things, eg mi profesor, el que enseña historia, es muy severo (my teacher, the one who teaches history, is very strict), mis amigos, los que viven en la casa enorma, tienen mucho dinero (my friends, the ones who live in the enormous house, have lots of money). They are not used very often in speech as it is more common to use que, but they are seen more often in written texts.
El cual, la cual, los cuales and las cuales mean exactly the same thing as el que, la que, los que and las que and work in exactly the same way. They are more likely to be seen in literary texts.
Complete the sentences with a suitable relative pronoun.