他们五人一组玩这个游戏。

They are playing the game in fives.

youdao

五人一组进行活动。

Work in group of five.

youdao

她们分成三、五人一组，等待着伴奏的音乐开始。

Separating into individual groups, they waited for the music to begin.

youdao

Well, a cross-sectional study would mean that you'd get a random group of the population and measure them in 1970 and then take another random group five years later and measure them, but it wouldn't be the same people necessarily, it would be different groups of people.

那么,横断面研究就是,1970年你在人群中随意选择一组人,并记录下相关数据,然后,五年后再随意选择一组人记录数据,但这不需要是同一组人,通常是不同的人

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选