Tom, clean up the broken glass _________ someone walks on it.
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.
With ____ leaves ____ in the earth every year, the soil becomes richer and richer.