treadmill
/ˈtredmɪl/noun
1- a device formerly used for driving machinery, consisting of a large wheel with steps fitted into its inner surface. It was turned by the weight of people or animals treading the steps.踏车（过去由人或牲口踩动踏板以驱动机器）。
1.1
- a similar device used today for exercise健身踏步车。
1.2
- figurative a job or situation that is tiring, boring, or unpleasant and from which it is hard to escape〈喻〉令人厌倦的工作; 单调的工作; 令人不快的情况：
the soulless treadmill of urban existence.
枯燥无味的城市生活。