前数

例句：

1. 1. We need to count the number of people in the room before we start.
   我们需要在开始之前数一下房间里的人数。
2. 2. The teacher counted the students as they entered the classroom.
   老师在学生们进入教室时点名。
3. 3. He estimated the cost of the project at $50,000.
   他估计这个项目的成本是5万美元。