This pair of trousers is very beautiful. May I ______ ?
--- When did your father come back last night?--- He didn’t come back _______ he finished all the work.
I think Kate will come if she _______ free this afternoon.
---I hope you _______ my party next weekend?--- OK, I _______ .
I was doing my homework _______ mother was cooking.
No one knows what _______ in fifty years.