n.曳光弹，示踪剂，同位素指示剂

The tracer bullet arced across the night sky.
痕迹弹在夜空中划出了一道弧线。
She used a pencil to trace the outline of the leaf onto the paper.
她用铅笔将叶子的轮廓描在纸上。
The detective was able to trace the source of the stolen goods.
侦探能够追踪到被盗物品的来源。
The artist traced her design onto the canvas before painting it.
艺术家在绘画前将她的设计草图描到了画布上。
The company uses sophisticated software to trace the movement of goods in its supply chain.
公司使用先进的软件来追踪其供应链中货物的移动。
We were able to trace the call back to a payphone in New York City.
我们能够追踪回电话到纽约市的一个公用电话亭。
The historian spent years tracing the lineage of the royal family.
这位历史学家花费数年时间追踪皇室家族的血统。
The GPS tracker allowed us to trace the location of the lost hiker.
GPS追踪器使我们能够追踪到失踪徒步者的位置。
Tracers in the water helped scientists understand ocean currents.
水中的示踪剂帮助科学家理解了海洋洋流。
The archaeologist carefully traced the ancient symbols etched into the stone.
考古学家小心翼翼地描摹刻在石头上的古老符号。