The most common cause of COPD is long-term smoking or years of exposure to second-hand smoke.

VOA: standard.2010.06.21

One is there's no lag period, notice that antibody levels start rising right away after the second exposure.

第一是没有迟滞期,请注意,抗体浓度迅速上升,在第二次接触抗原时

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The response to the second exposure in antigen is different in a couple of ways.

第二次接触相同抗原,免疫系统的应答,在以下几个方面是不同的

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The second part of the question dealt with the changes in our exposure to foreign assets and that's an area that we've been very interested in.

第二个问题是关于,我们在国外资产投资上的变化,这一直是我们很感兴趣的领域

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Because on second exposure there's another population of cells that I haven't mentioned before that remain after the primary exposure and those are called memory cells, they're down here.

因为在再次免疫中,有另外一些细胞,我之前并没有提到过它们,在初次免疫结束后保留下来的细胞,被称为记忆细胞,它们在下面

耶鲁公开课 - 生物医学工程探索课程节选

Now, why is the time less on second exposure?

为什么再次免疫花费的时间少呢?

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