The Maya poured the chocolate drink back and forth between two containers so that the liquid had a layer of bubbles,or foam.

VOA: special.2010.02.17

We'll pull back that layer before long.

我们不久后会撤销那一层。

哈佛公开课 - 计算机科学课程节选

And so if we wanted to do this here, it's again, the same thing we're just now pulling back this layer and calling them char *s not actually strings.

如果我们想要在这里这样做，再次，我们撤销这一层,把它们叫做char，*s，实际上不是字符串。

哈佛公开课 - 计算机科学课程节选