When she was alone at home,Mary needed a friend __________.
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.
None knows if _______ that boy, but if _______ him, her parents will be disappointed.