workhorse

workhorse
noun
  1. a horse used for work on a farm
    役马;耕马
    ■a person or machine that dependably performs hard work over a long period of time
    (人)工作吃重的人,吃苦耐劳的人;重负荷的机器
    the aircraft was the standard workhorse of Soviet medium-haul routes.
    该型飞机是苏联中程运输线上的标准运输工具。
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