This suggests that they're not seeing each other's goods; they're not trading them.

这说明他们并没有,看到过彼此的商品,他们之间没有贸易往来

耶鲁公开课 - 古希腊历史简介课程节选

It's 109 . 5 is what we would expect for methane because it's tetravalent, but here we're just seeing something that's divalent, and they're both in p orbitals that are perpendicular to each other.

因为甲烷是四价的，我们预测是109。,但这里我们，看到的是二价的，它们都在。

麻省理工公开课 - 化学原理课程节选