a person or thing that traces something or by which something may be traced, in particular
追踪者，追踪装置，尤指：
a bullet or shell whose course is made visible in flight by a trail of flames or smoke, used to assist in aiming
曳光弹。
a substance introduced into a biological organism or other system so that its subsequent distribution may be readily followed from its colour, fluorescence, radioactivity, or other distinctive property
示踪剂，显光剂。
a device which transmits a signal and so can be located when attached to a moving vehicle or other object
跟踪器（安装在移动车辆上或其他物体上，通过其发出的信号进行跟踪）。
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tracern.追踪者；追踪装置；示踪剂；曳光弹；显光剂；跟踪器
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tracev.找到；发现；映描；描摹；跟踪；追踪；追溯；描绘；查考；追究
