You ought to ask for your teacher's permission. ✬

You shouldn't read people's private letters without permission. ✬

Did you get permission to park here? ✬

I'll get permission from my superior. ✬

No one is to leave without permission. ✬

You must not park your car there without permission. ✬

Hackers break into computers without permission. ✬

Don't enter the room without permission. ✬

I've been given permission to inspect this equipment. ✬

You have to ask for permission from your teacher. ✬