The researchers did a study of adult beliefs about the possibility of health risks to children from third-hand smoke.

VOA: special.2009.01.07

if we do introduce a third possibility-- I'm not sure this is the right thing.

如果确实加入这一种可能-,我不确定这是对的。

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And the third possibility, is to do the expected case.

第三种方法，就是针对给出的例子。

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