number of serviceable cars held kept

例句：

1. 1. The number of studentsin the class is 20.
   班上的学生有20个。
2. 2. Thenumber of books on theshelf is 50.
   书架上的书有50本。
3. 3. Thenumber of cars on the road is increasingrapidly.
   路上的汽车数量正在迅速增加。