The old professor gave a long _______ lecture,and made us so _______ that we all felt sleepy.
He __________ that until he __________ the directions once again.
When they met again in New York, ten years __________.
__________ the time the firemen arrived, the building had been burnt to pieces.
__________ industry develops quickly, more and more rivers are being polluted.
Most Chinese musical instruments are quite different __________ western ones __________ shape.