• CUYO/A/S is the equivalent of 'whose' used as a relative in English (not for questions):
|Es un autor cuyos libros conozco bien.
BUT: ¿De quién es esta pluma?
|It's an author whose books I know well.|
Whose pen is this?
• Both neuter forms LO CUAL and LO QUE are used in
clauses, set off by a comma,
referring back to a previously stated idea. In this usage they correspond to the English which:
|Creen que soy brillante, lo cual es cierto.
Hay nubes, lo que indica lluvia.
|They think I'm brilliant, which is true.|
There are some clouds, which indicates rain.
• LO QUE means what in noun clauses:
|Esto es lo que contesta.
Lo que pensamos no es importante.
|This is what he answers.|
What we think is not important.
• TODO LO QUE means all that or everything that:
|Todo lo que escribe es bueno.
||Everything (that) she writes is good.|