Unlike a vault, the truss exerts no thrust But only downward pressure; supporting walls require no Buttressing or extra thickening.
同拱顶不同的是桁架不承担推力而只承担向下的压力，不需要扶壁或其它特别的加固物来支撑墙体。
All of sudden, there came a terrible thunderclap about fifty feet directly above our heads, and a bolt thrust downward like sharp sword. The sky was brought into pieces.
突然，在我们头顶五六丈的上空，发出一声可怕的霹雳，闪电像利剑一样直插下来，天空被彻底吹裂了！
All of sudden, there came a terrible thunderclap about fifty feet directly above our heads, and a bolt thrust downward like sharp sword. The sky was brought into pieces.
突然，在我们头顶五六丈的上空，发出一声可怕的霹雳，闪电像利剑一样直插下来，天空被彻底吹裂了！
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