it's this paper mend with a plastic cover and there's all these black magnetic particles here.

它是用这种纸以及一种塑料覆在上面,这里还有一些黑色磁性粒子。

哈佛公开课 - 计算机科学课程节选

And so it has what? In contrast to the sigma, it has a nodal plane containing both nuclei.

这是什么，和sigma相反，它是包覆在核上的平面电子云，有一个界面。

麻省理工公开课 - 固态化学导论课程节选

You need to do that to be able to control the shield that's as big as that and as heavy as that, because it is made fundamentally of a heavy wood, typically covered by leather, sometimes with some bronze, a bronze sheet across the front of it as well.

如果你想自如操控这块盾牌就必须得这样,这种盾牌很大并且很笨重,因为它主要是由沉重的木材制成,表面一般覆有皮革,或包上铜皮,就是表面上有一层铜皮

耶鲁公开课 - 古希腊历史简介课程节选