Route the wiring and make the neccessary connections. Do not allow the wiring to restrict free rotation of the slip ring.

把导线排好并做必要的连接，防止导线妨碍电气滑环的自由旋转。

Meanwhile the indifference curve also shows that it is not neccessary to change the security combination when such changes in return possess similarity.

然后引入无差异曲线来说明市场中证券期望收益率同方向变化且变化值相差不大时，不必改变证券组合。