play pendulum

例句：

1. 1. Thependulum swings back and forthin the breeze.
   风中，摆锤来回摆动。
2. 2. Thescientist used a pendulumto measure the speed of light.
   科学家用摆锤测量光速。
3. 3. The pendulum was used as a clock mechanism.
   摆锤被用作时钟机制。