When a baby is put face down in a bed, it begins to re-breathe carbon dioxide, which is toxic.

VOA: standard.2010.02.08

And in terms of thinking about it for organic chemistry or if you're interested in thinking about the mechanism maybe by which it is toxic, a first step would be to draw its Lewis structure.

而为了在有机化学中思考它,或者如果你对它,有毒的机理感兴趣的话，第一步要做的应该就是画出它的路易斯结构。

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However, their biological relatives in Mexico would presumably have that same risk, but it would never be manifested if they're not exposed to what some have called a toxic food and physical activity environment.

而且,他们远在墨西哥的血缘亲属,可能也面临同样风险,但他们面临着所谓的有毒食物和活动环境,这个说法就不会得到证实

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