来自《耶鲁大学开放课程：环境政治与法律 第1集 第1集》
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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 -
It's one of the easier ones to identify.这是非常易于辨认的 -
In fact, with diesel exhaust,实际上 在柴油废气中 -
you cannot only see it,你不可能仅仅看见它