短語詞組短語lower -chord panel point [建]下弦節(jié)點(diǎn)lower chord length 上弦桿長(zhǎng)度lower chord member support 下承式lower chord panel points 桁架的下弦桿節(jié)點(diǎn)lower chord bracing 下弦支撐upper and lower chord 上下弦roof truss lower chord elevation 屋架下弦標(biāo)高 返回 lower chord