Count off

动词 count off:

1. call in turn from right to left or from back to front numbers that determine some position or function

1. The soldiers counted off from the left by four.
   士兵们从左起四个一组大声报数。
2. At the beginning of each class, I count off the students.
   每节课开始的时候我都先数一下学生人数。
3. Count off by threes!
   一至三报数！