on the sofa还是on a sofa

on the sofa还是on a sofa on the sofa还是on sofa对? in the sofa 还是 on the sofa? in the sofa还是on the sofa 是sit in the sofa 还是sit on the sofa? 是on the sofa还是in the sofa? 是用in the sofa还是on the sofa? ( ) Jill( ) on the sofa? Thepen is on the sofa对on the sofa提问 what\'s on the sofa? fell asleep on the sofa It's on the sofa.