单项选择题That noise is getting louder because the engineers are () the engine to see if the plane is ready to fly.
单项选择题He was very much disappointed because () went to his wedding party.
单项选择题() they reached the small village before dusk.
单项选择题Themayor promised to take effective measures to () the city.
单项选择题They are tearing () these old houses to put up a new shopping center.