Finding in-formation in today's world is easy. The _____ is how you can tell if the in-formation you get is useful or not.
The student must have been ill yesterday, ______?
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).