Explications :
since est utilisé pour une date ou un complément circonstanciel de temps alors que for est utilisé pour une durée.
par exemple : since 2021 ; for 10 years
Ex 1 :
1. Joe is at this school for five years
2. Where's Alison ? I don't see her since this morning.
3. Mr.Wayne know his wife since they were both small children.
4. Ben don't see his uncle for several years.
5. I am not very well since Monday.
6. My brother had his new mountain bike for two weeks
7. They live here since they first came to Britain.
8. The poor animal is very hungry. It doesn't have anything to eat since days.
J'espère que ça t'aura aidé :))