Traduire en français des dialogues avec for ou since Traduction

Quelle est la traduction française de chacun des dialogues suivants ?

- Since when have you been there?
- I have been there since 10 a.m.

- How long have you known Jack?
- I have known Jack for three months.

- How long will you be gone for?
- We will be gone for five days.

- How long did she work there?
- She worked there for twenty years.

- Since when have they played the guitar?
- They have played the guitar for eight years.