Radioactive tracer
[化] 放射性示踪剂
🧩 词语组成解析
tracer
['treisə]
n. 追踪者，描图者，（铁笔等）绘图工具;
🗣️ 情景例句
Those were great days and we were very happy.
那些日子美好极了，我们过得很幸福。
What did the doctor say?
医生怎么说？
the gaoler returned a few moments later with a pair of glasses and the usual copy of the letter which he proceeded to read to the prisoner.
一会儿工夫，狱卒重新登台，拿来一副眼镜以及平时使用的那封信，然后为那囚犯念了起来。