When it comes to gossip(流言蜚语), learn to keep your mouth shut ________ you'll avoid trouble.
We have produced 15% more cotton this year____ we did last year.
The teacher is busy ____ correcting papers.
____ the problem of method is solved, talking about the task is useless.
Where have you been ____ you left home?
____ you told me, I had heard nothing of what happened.