他们设计的公路还有轻微的路拱或弯拱曲线，便于路面排水。

Their roads were also slightly curved in a crown or camber so that the water would run off.

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俯首，弯身：头或身体的低或弯，如点头或鞠躬。

To lower or bend the head or body, as in a nod or bow.

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安装位置距泵出口或弯管下游处最少应该有5倍管道直径的长度的位置。极端情况下可能需要安装流向矫直装置。

Install 5 pipe diameters minimum downstream from pump discharge or elbows to avoid flow turbulence. Flow straighteners may be required in extreme cases.

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