开始时，双脚前后站着，把身体的重量前后甩动（与绕圈甩动不同）。

To start, stand with one foot in front of the other and shift your weight back and forth (versus around in a circle).

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正是这一洞见使得冰岛从1900年前后欧洲最贫穷的国家之一转变为2000年前后最富裕的国家之一。

This insight is what led Iceland to go from being one of the poorest countries in Europe circa 1900 to being one of the richest circa 2000.

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经过测量反应前和反应后实验前后的可乐pH值发现前后酸性没有发生变化，排除了简单的碳酸反应导致这喷泉影响的想法。

Measurements of the pH of the Coke before and after the experiments showed that its acidity did not change, ruling out the idea that a simple acid-base reaction drives the fountains.

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Long before Milton had begun to tackle the problem, Christians had for centuries, for millennia, puzzled over the logical inconsistency between these two concepts.

早在弥尔顿应对这个问题之前，基督教徒们就已经花了成百上千年，为这两个概念之间逻辑上的前后矛盾感到困惑。

耶鲁公开课 - 弥尔顿课程节选

In between those two parts I will ask that anyone who is shopping the class and would like to leave at that time do so then.

在前后两部分之间,请来试听并且想离开的同学在那时候离开,如果你能尽量等到那个时候。

耶鲁公开课 - 1945年后的美国小说课程节选

So you can imagine a bead with a wire going through it and the bead can only slide back and forth.

你可以想象一个穿在绳子上的珠子,小珠只能前后滑动

耶鲁公开课 - 基础物理课程节选