I was happy.
I wasn't happy
Was I happy?
You were a student last year.
You weren't a student last year.
Were you a student last year?
He/she was （wasn't)crying just now.
Was he/she crying just now?
We/they were(weren't) frendly to me.
Were we/they frendly to me?
回答Yes(no),I/she/he was(wasn't)
Yes(no),we/they were(weren't)