Priciple of least distance 原理是由（）提出

Plot bending moment diagram by the priciple of superposition. Point out the maximum value of bending moment.[img=399x142]17de840991be96f.png[/img][img=125x35]17de84099cddd9c.png[/img] 未知类型：{'options': ['', '', '', ''], 'type': 102}