serial arithmetic unit

例句：

1. 1. The serial number of the car isXYZ.
   这辆车的序列号是XYZ。
2. 2. They worked on a series ofprojects over the summer.
   他们在夏天完成了一系列的项目。
3. 3. The sequence of events led to thediscovery of a new drug.
   一系列事件导致了新药物的发现。