—Who telephoned you just now?— don’t know. I was about to answer the phone when it ________.
If you ______ earlier, you ________ him.
Great changes __________ in our hometown in the past twenty years..
John, look at the time. ________ you play the piano at such a late hour?
He looked as though he _________ a ghost(鬼).
He stood for an instant with his hand still ___________.