单项选择题
A.led B.changed C.filled D.proved
A.There are larger populations in cities. B.The air in the city is dirty. C.There are more cars in the city. D.There are much more gas fumes from car's and burning of coal and oil for energy in the city than in the country.
A.if the minimum wage is set too high B.if the minimum wage is set too low C.if the workers are unskilled D.if the maximum wage is set