Flat tube in any cross section are oblong, the length of the shaft according to the tube pitch to determine the size of.
扁管在任何一个截面均为长圆形，其长短轴根据管心距的大小来确定。
Flat roofs may either be dead level or (preferably) have some degree of pitch to them so that rainwater and melted snow can drain away.
平屋顶可以为完全水平，也可以(这样更好)具有一定程度的坡度，以便雨水或融雪得以排除。
Flat roofs may either be dead level or (preferably) have some degree of pitch to them so that rainwater and melted snow can drain away.
平屋顶可以为完全水平，也可以(这样更好)具有一定程度的坡度，以便雨水或融雪得以排除。
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