使用寿命02:useful timeRelative explainations: The useful life of a car.汽车的使用寿命The useful life of the equipment depend mainly on the maintainability.设备的使用寿命主要取决于维修保养条件。It's only the gold mounting that pushes the price of this model up. For quality and length of service there's nothing to choose between this and the cheaper pen.然而就质量和使用寿命而言，这种钢笔和那种便宜些的没有多大差别。average life平均寿命mean lifetime平均寿命Use of a device or component at a lower current, voltage or power level than it can handle, in order to give longer life or reduce occurrence of stressrelated failures.使用比设备或元件可以承受的要小的电流、电压或功率，以便提高延长使用寿命或减少出现由于应力而产生的故障。The service life of a machine depends chiefly upon how it is being used.机器的寿命主要取决于它如何使用。Water is also used as a coolant for rolling- mill roll to maintain their contour and lengthen their service life.热轧机的轧辊也需用冷却水来保持轧辊的外形和延长它的使用寿命。catalyst life催化剂寿命engine life发动机寿命
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