serial I-O command

例句：

1. 1. The serial numbers of the products are printed on the boxes.
   产品的序列号印在盒子上。
2. 2. The sequence of events is important for understanding the cause of the accident.
   事件的顺序对于理解事故的原因很重要。
3. 3. The serial number helps us to identify the product quickly.
   序列号帮助我们迅速识别产品。