By working slowly but surely towards your goal, you'll___________succeed. 

A. eventually       B. accidentally       C. occasionally         D purposely

日常所接触到的许多机器，电动机输出地功率和转速都是经过带传动传递到齿轮箱上，通常齿轮箱输入轴的转速要比电动机输出轴的转速（）。