致癌物为某些水平接触下导致癌症的物质。

Carcinogens are substances that can lead to cancer under certain levels of exposure.

youdao

没有迟滞期，注意抗体水平在第二次接触后立即开始上升。

There's no lag period, and notice that antibody levels start rising right away after the second exposure.

youdao

这是不可能的，因为会有更多的雇主有更多的机会接触到比平均水平高得多且廉价的外国劳动力、机器人、软件、自动化技术和人才。

It can't when so many more employers have so much more access to so much more above average cheap foreign labor, cheap robotics, cheap software, cheap automation and cheap genius.

youdao

Some, like the smallpox vaccine on one exposure generates a very high response that lasts for many years so you don't need a boost.

有一些疫苗,比如接触一次天花疫苗后,人体就能产生高水平的免疫应答,并持续很多年,所以无需再次接种

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