Undo the last command
取消上一个命令

　 UndoMultiple

Provides a list of commands you can undo.
列出可执行Undo的命令

UnifyMeshNormals

Unify polygon mesh normals
统一多边形网格物体的法线方向

　 Units

Set the units and tolerance for the model
设定模型尺寸单位及公差

UnLock

Unlock locked objects
解除物体的锁定

UnLockSelected

Unlock selected locked objects
解除所选择物体的锁定

UnrollSrf

Unrolls (flattens to a plane) a surface.
将物体卷展成一平面

Untrim

Untrim a surface
反修剪表面（对应于Trim）