第二组背完了，将第一组和第二组混合，复习这两组。

After you finish memorizing the second pile, mix the first and second pile together, and review both of them.

youdao

经过八周的实验，相比较于第二组暴露在自然光——黑暗循环下的老鼠，第一组和第三组的老鼠体重的增长幅度高出50个百分点。

Over the eight-week period of the experiment the mice inthe first and third groups gained almost 50% more weight than those exposed tothe natural light-dark cycle.

youdao

在她们发表于《进化与人类行为》刊物上的实验中，她们将96名男女学生分为三组，除第三组外，第一组和第二组接受专业按摩，然后第一组和第三组开始玩“信任游戏”。

The first and second received a professional massage but the third did not. Then the first and third group took part in a “trust game.

youdao

All of these from the group one and two through the group five and six elements, but what about elements, what about molecules like hydrogen, or nitrogen, or maybe oxygen?

所有的这些都是来自于第一主族和第二组主族,到第五主族和第六组主族的悬殊，那么元素呢，比如氢气，氮气或氧气那样的分子呢？

麻省理工公开课 - 固态化学导论课程节选