地球引力

例句：

1. 1. The Earth's gravity is strong enough to hold the moon in orbit.
   地球的重力足以将月球保持在轨道上。
2. 2. Gravity plays a crucial role in the formation of planets and stars.
   重力在行星和恒星的形成中起着至关重要的作用。
3. 3. The gravitational pull between two objects can be used to calculate their distance.
   两个物体之间的万有引力可以用于计算它们之间的距离。