.When _____ my childhood, I get lost in happy memories of times now gone forever.
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.