I ______ have been more than six years old when the accident happened.
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.”
It was when she was about to go to bed ______ the telephone rang.