German phrase
Gehören Sie zu ~?
Meaning
Are you part of ___?
When to use it
This asks if you belong. It is polite and formal for checking group membership.
Example dialogue
Gehören Sie zu unserer Austauschgruppe?
Are you part of our exchange group?
Ja, ich bin seit diesem Semester Mitglied.
Yes, I have been a member since the start of this semester.