Bonjour je ne comprends pas cette exercice pouvez-vous m’aider svp merci beaucoup d’avance

Bonjour
LES PRONOMS RELATIFS
1- It's a wonderful book which tells the story of Charlie Chaplin.
2- Thank you for the book that you gave me.
3- Our train is the train which leaves from platform 5.
4- Mrs Hamilton is the teacher whom / ou / that you saw at the station.
-
bonne soirée ☺☺☺