inflexion of the verb

例句：

1. 1. The curved path of the river is a natural inflexion.
   河流的弯曲路径是一个自然的曲率。
2. 2.The car's steering wheel has an inflexion that makes it easy to turn.
   汽车的方向盘有一个曲率，使得转向变得容易。
3. 3. The melody of the song has a subtle inflexion that adds depth to the performance.
   歌曲的旋律有一个微妙的曲率，为表演增添了深度。