Tracer elements
[医] 示踪元素
🧩 词语组成解析
tracer
['treisə]
n. 追踪者，描图者，（铁笔等）绘图工具;
n. 原理, 基础
🗣️ 情景例句
I want to keep the after-school programs--
我要保存这些课外活动--
The view was terrific.
景色美极了。
Though the sound could be heard clearly, it took me a long time to react.
虽然声音听得很清楚，但我过了好一会儿才作出反应。