The researchers say the bacteria were grouped together in a thin, but sticky area of cells on the inside of showerheads.

VOA: special.2009.10.13

Versus looking at, for example, helium or neon or argon, these are all inert gases, inert meaning essentially do not react, those were grouped together in the periodic table.

相反，他发现氦，氖，氩，都是惰性气体，惰性的意思是基本不参与化学反应，因此把它们放在周期表中的同一类里。

麻省理工公开课 - 化学原理课程节选

- 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。

麻省理工公开课 - 化学原理课程节选