单项选择题
A．going B．came C．go D．coming
A．a luxury may change into a need which most people want to get B．the basic needs are getting smaller and smaller C．a luxury and the basic needs can be exchanged D．the basic needs can be changed into a luxury
A．has had chemicals and fertilizers added to it B．contains vegetable matter that has not been consumed C．has been nourished by fertilizers D．already contains large quantities of vitamins and minerals