Lack of money _____ her not continuing her studies.
I think, though I could be mistaken, ______ she liked me.
Everyone knows, perhaps except you, _______ your girl-friend is a cheat.
Someone is ringing the doorbell. Go and see ______.
It was ten o’clock _____ he came back home.
“Where _______ go to work?” “Where _______ go to work is not known.”