短语词组短语beam -on-foundation 地梁Beam Always On 光束总是开启Beam Ca on 光束加农炮beam element on elastic foundation 弹性地基梁单元beam on two supports 两端支撑梁straight beam on curve 曲线直梁beam on alternate frames 间肋梁beam on spike wave 棘波分析地形图 返回 beam on