题目

在生产生活中.使用如图所示的简单机械，一定能省距离的是A.扳手B.斜面C.滑轮组D.食品夹 答案：【答案】D【解析】根据W=Fs可知，机械要省距离，则要费力。A．B．C．扳手、斜面、滑轮组在使用时能省力，但费距离。故A、B、C错误。D．食品夹在使用时动力臂小于阻力臂，属于费力杠杆，能省距离。故D正确。I have to make a phone call. Can you wait a few minutes? It ________ long. A. won't be taking B. isn't taking C. doesn't take D. won't take