The simple mechanical pump draws water from a shallow well or nearby stream or river for use in irrigation.

VOA: standard.2009.12.18

Here's a really simple example. Mixing of oil and water.

这有一个很简单的例子，水和油的混合。

麻省理工公开课 - 热力学与动力学课程节选

Here's a really simple example. Mixing of oil and water.

这有一个很简单的例子，水和油的混合。

麻省理工公开课 - 热力学与动力学课程节选