A colorless gas that is present in the air in trace amounts.
空气中存在的无色微量气体。
This element occurs naturally in trace amounts in the environment.
这自然会出现的微量元素在环境中的数额。
You don't have to worry, we're definitely talking about trace, trace amounts.
但你不必担心，我们所说的绝对是非常，非常微量的。
They're trace levels but of course with radioactivity we can measure very low amounts.
这些微量放射性物质达到了检出水平，我们当然能够检出极低含量的放射性。
They're trace levels but of course with radioactivity we can measure very low amounts.
这些微量放射性物质达到了检出水平，我们当然能够检出极低含量的放射性。
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