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

A to B is one distance, which is a large one, and B to C is only half that distance, and that's because of the way the Greeks laid this thing out with their two to one ratios, three to two ratios and so on.

到B是一个距离,比较大,而B到C只有半个距离,因为希腊人,用诸如二比一,三比二,之类的频率比来安排音阶

耶鲁公开课 - 聆听音乐课程节选