Relier deux idées
1 · Reason: why?
Parce que introduces a clause with a subject and verb. À cause de introduces a noun phrase, usually for an unwelcome cause.
Nous changeons de salle parce que le chauffage est en panne.We are changing rooms because the heating is broken.
Nous changeons de salle à cause de la panne.We are changing rooms because of the breakdown.
2 · Result: what follows?
Donc presents the second idea as a consequence of the first.
Le chauffage est en panne, donc nous changeons de salle.The heating is broken, so we are changing rooms.
3 · Concession: what is surprising?
Pourtant signals an outcome that goes against an expectation raised by the first statement.
Le projet coûte cher. Pourtant, le comité l’a accepté.The project is expensive. Yet the committee accepted it.
4 · Purpose: what is the aim?
Use pour + infinitive when the same person does the action and pursues the goal. Use pour que + subjunctive to give another subject its own verb.
Lina parle lentement pour être comprise.Lina speaks slowly to be understood.
Lina parle lentement pour que nous puissions la comprendre.Lina speaks slowly so that we can understand her.
5 · Addition: one more point
De plus adds information. The second fact need not follow from the first.
Le service est gratuit. De plus, il est ouvert le samedi.The service is free. It is also open on Saturdays.