Movement down a concentration gradient occurs fairly rapidly over short distances like a micron or so, like the size of a bacterium.

顺浓度梯度扩散在一微米左右的短距离内,相当迅速,一微米相当于一个细菌的大小

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It may not be as the crow flies and may be long way around,

它可能不是直线最短距离，可能绕得很远，

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