每个班四十名学生被分成四组，每组十人。

In each class, forty pupils are divided into four groups of ten.

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被回顾的各个研究，其形式一般是询问父母孩子上日托班和幼儿游戏组的情况，而结果随研究的开展日期，持续时间，与其他孩子交往程度不同而不同。

The studies -- in which parents were asked about day care and playgroup attendance -- varied when it came to the timing, duration and extent of social interaction with other children, the researchers.

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萨班卡亚是一组复火山的一部分，这组复火山包括了附近另外两座更老的火山，然而这两座在历史记载中从未喷发过。

Sabancaya is part of a volcanic complex that includes two other nearby (and older) volcanoes, neither of which has been active historically.

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