It had been proved that the curvature tensor is a curl(grad),not zero except in Eucldean space,and so discovered the essence of Bianchi identity:div(rot(grad))=0,the curvature,forming tube field,is invariant along the tube,i.是什么意思_It had been proved that the curvature tensor is a curl(grad),not zero except in Eucldean space,and so discovered the essence of Bianchi identity:div(rot(grad))=0,the curvature,forming tube field,is invariant along the tube,i.在线翻译_英语_读音_用法_例句