来自《耶鲁大学开放课程：环境政治与法律第1集第1集》

appear on their radar screen.

出现在他们的雷达屏幕上
They decide what monitoring programs are necessary

他们决定哪些监控项目是必要的
in order to detect where they go, how they move,

目的是探测到它们会去哪里它们如何移动
how they behave in the environment

它们在环境中如何作用
and how dangerous they are, who might be at risk.

它们有多危险谁会处于风险中
One good example of that might be diesel exhaust.

一个好例子可能就是柴油机废气
And you may know that the older trucks,

你们也许知道那些老式的卡车
the less efficient diesel vehicles,

那些效率较低的柴油车辆
tend to spew large particulate matter from their tailpipes.

从它们的排气管中喷出大颗粒的废气
And these larger particulates, ten microns in size and larger,

这些较大的颗粒 10微米或更大
are visible.

肉眼可见
It's one of the chemical threats that is visible.

这是一个可见的化学威胁