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。

youdao

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。

youdao