number of major currencies

例句：

1. 1. The number of students inthe class is 30.
   班级里的学生有30名。
2. 2. Thenumber of cars on theroad has doubled since lastyear.
   路上的汽车数量比去年增加了一倍。
3. 3. The number of employees at thecompany has increased by 20%this year.
   公司的员工人数今年增加了20%。