Bonjour voici mes réponses !
Réponses :
1) The bike wich I came to school with has a flat tyre.
2) The armchair where I was sitting on collapsed.
3) The woman who you will talk to is the CEO of the company.
4) I need to make an appointment with the doctor who you were sitting next to yesterday.
Explications :
Les pronoms relatifs en anglais sont : who, whom, which, whose, where et when.