Question

Were you at school yesterday? was your mother at home on saturday? were you with your friend last night? were you in bed early on sunday?

Answer 1

1) Yes, I was. I was at school yesterday.
2) Yes, she was. My mother was at home on Saturday.
3) No, I wasn't. I wasn't with my friend last night.
4) Yes, I was.   I was in bed early on Sunday. 

Answer 2

Yes, I was at school yesterday. No, my mother was not at home on Saturday, she was out running errands. Yes, I was with my friend last night. No, I was not in bed early on Sunday, I stayed up late watching a movie.