拐点

例句：

1. 1. The mountain is at its apex of the valley.
   这座山是山谷中的最高点。
2. 2. The eclipse occurred at the apex of the moon's shadow.
   日食发生在月亮阴影的顶点。
3. 3. The project reached its apex in the final year.
   该项目在最后一年达到顶峰。