A symmetrical body rotating about an axis one point of which is fixed is called a top .

形状 对称的一物体绕其轴转动，若轴上一点固定不动，则这个物体就叫做 陀螺。

The movement of symmetrical top is used as an example to discuss the advantage and problems of attitude simulation with quaternion method .

以 对称 重 陀螺为例，探讨了四元数在刚体姿态仿真中的应用及应用中存在的问题。

FIGURE 7 . Typical symmetrical distribution of seborrheic dermatitis on the head ( top ) and on the body ( bottom ) .

图-7（ 头） 皮屑和瘙痒-脂溢性皮炎在人体的头部、身体多发部位。