If we do not deal with ________ problem caused by air pollution, our planet may no longer be ________ healthy place for us.
_______ the tower building,where you can see the whole city.
Why did they keep trying _________ they must have known it was hopeless?
Having got up late this morning, Mike ran as fast as he could _______ to catch the bus.
Their products enjoy 30 percent_____ of the market in this country because both the quality and their service are fine.
Although I admire you _____ your work on soil, I think you should apologize _____the villagers for the water pollution.