He also discovered Facebook is bucket testing this feature with certain groups of users as the object wasn't appearing every time Tal refreshed the page he was looking at.

他同时发现Facebook针对特定用户群进行了小范围的测试。因为这个对象并不是每次刷新的时候都会出现。

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As with all diseases, certain groups will be more at risk than others.

所有的疾病都是如此，一些人比另一些人更容易受到威胁。

《牛津词典》

On the other hand, there are individuals that very clearly demonstrate who they are by their identification with certain social groups.

另一方面，有些人则通过他们与某些社会群体的认同而明白无误地来表明他们是何种人。

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Lisa Curtis is an analyst at the Heritage Foundation: "When somebody like Shahzad is easily able to find training and inspiration and easily connect up with these various militant groups in Pakistan,it shows that there is a certain level of tolerance for terrorist groups in the country."

VOA: standard.2010.05.18

Yes, there is scads of research out there about how certain groups are perceived with a negative bias.

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For instance, the penalty will be waived for people with very low incomes who are members of certain religious groups, or who face insurance premiums that would exceed 8% of family income even after including employer contributions and federal subsidies.

CNN: Emotions high after Supreme Court upholds health care law

It can be a problem for funds that target certain foreign markets, specific industry groups or smaller companies with less trading volume.

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