tangency point的用法和樣例：
例句
- The tangency point is known as the pitch point.
兩節圓的切點(diǎn)成為節點(diǎn)。 - The steamline curve ratio in the bucket of a spillway gradually changes in the flow direction, but the wall curve ratio changes in the point of contact of the bucket suddenly.
溢流反弧段流線(xiàn)的曲率呈沿程變化，而反弧上下切點(diǎn)位置處邊壁曲率卻發(fā)生突變。
