1) ?: Was I having supper when you rang me up? -: I was not having supper when you rang me up.
2) ?: Was his mother making dinner in the kitchen, when he came? -: His mother was not making dinner in the kitchen, when he came.
3) ?: Were your friend smoking in the corridor when we saw them? -: Your friends were not smoking in the corridor when we saw them.
4) ?: Was I hurrying to the University when I met Pete? -: I was not hurrying to the University when I met Pete.
5) ?: Were we having our English at 10 in the morning? -: We were not having our English at 10 in the morning.