What this does, when you use relative risk you take some group of the population and you establish their risk as--at one.

当运用相对危险度这个概念时,要选定一个群组,并把这个群组的风险设为1

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- So, for example, if he was talking about the group one metals, he noticed these were all very soft reactive metals, those were grouped together.

比如，他在讨论，I，族金属，注意到它们都是质地较软的活性金属，这些被归到一类。

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