number state

例句：

1. 1. The number of students in the class is 30.
   班级里有30名学生。
2. 2. The number of people who signed up for the event was over 500.
   报名参加该活动的人数超过500人。
3. 3. The number of stars in the sky can be counted on one hand.
   天上的星星数量可以用手指头数得过来。