题目

Many citizens hope that the government can do something to keep the prices of goods ________ in order that their life will not be affected.   A. stable                 B. permanent            C. still                D. balanced 答案：A下列物体在运动过程中，不计空气阻力，机械能守恒的是A．被起重机拉着向上做匀速运动的货物 B．一个做平抛运动的铁球C．沿粗糙的斜面向下做匀速运动的木块D．在空中向上做加速运动的氢气球