Usages of which
My uncle explains how I can cross the street and which bus I should take.
Mi tío me explica cómo puedo cruzar la calle y qué autobús debo tomar.
This is the book which my friend recommends.
Este es el libro que mi amigo recomienda.
Elon.io is an online learning platform
We have an entire course teaching Inglés grammar and vocabulary.