serial and rotation numbers

例句：

1. 1. The serial numbers on the watch indicate the age of the watch.
   手表上的序列号表示手表的年龄。
2. 2. The series of photos document the journey from start to finish.
   一系列的照片记录了从开始到结束的旅程。
3. 3. The scientist conducted a series of experiments to test his hypothesis.
   科学家进行了一系列的实验来测试他的假设。
4. 1. The car's engine is designed for high-speed rotation.
   汽车引擎设计用于高速旋转。
5. 2. The machine has a built-in rotation system that allows it to rotate continuously.
   这台机器内置了一个旋转系统，可以连续旋转。
6. 3. The team rotated players to ensure everyone had a chance to play.
   团队轮换球员以确保每个人都有机会上场。