题目

The car accident on the main road the other day ____ the careless driving of a driver. A. was due to   B. resulted in    C. led to    D. was resulted from 答案：A 解析: 略如图所示，用相同的滑轮和绳子分别组成的甲、乙两个滑轮组，把相同的钩码提升相同的高度，在不计绳重及机械摩擦的情况下，甲所用的拉力    乙所用的拉力；甲滑轮组的效率    乙滑轮组的效率（填“大于”、“等于”或“小于”）．