Another recent study found that a single tillage does not harm yield or soil structure in land that is normally not tilled.

VOA: special.2010.09.28

Step three in our Lewis structure rules is to figure out how many electrons we would need in order for every single atom in our molecule to have a full valence shell.

路易斯结构规则的第三步是,找出让分子中每个原子的价壳层,都排满应该需要多少个价电子。

麻省理工公开课 - 化学原理课程节选

And resonance is the idea that sometimes one single Lewis structure does not adequately describe the electron configuration around a given molecule, so instead you need to draw two different Lewis structures to describe that more appropriately.

而所谓共振态,就是有时候一个路易斯结构不足以,完整描述一个给定分子的电子排布，因此这时你需要同时画出两个,不同的路易斯结构来描述它,这样会更恰当。

麻省理工公开课 - 化学原理课程节选