假如你让电影倒带播放，你会发现任何事情都带有明显的时间方向性质，就像有东西拉着他们：时间箭头。

If you look at a movie that's being played backwards, you know it immediately because most things have a distinct time direction attached to them: an arrow of time.

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即渗滤液性质对包气带介质中有机物含量具有方向性的影响作用，而包气带介质亚粘土比细砂更容易放大这种作用效果。

It means that the property of landfill leachate influences the organic matter content in the vadose zone; furthermore silt would more likely exaggerate the effects more than clay.

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Synthesis always occurs in one direction and that makes sense to you now because you know there's a directionality and the chemistry is different going one way than the other and this DNA polymerase only works on the chemistry going in one direction.

NA复制过程是单向的,现在你们该明白原因了,因为DNA单链有方向性,DNA在两个方向上化学性质不同,DNA聚合酶,只在一个方向上起作用

耶鲁公开课 - 生物医学工程探索课程节选