Pupils是可数名词吗

例句：

The school began in 1920, with only ten pupils.

这所学校创建于1920年，当时只有十名学生。

Several pupils were designated as having moderate or severe learning difficulties.

几名学生被认定有一定或严重学习困难。

The school has come under attack for failing to encourage bright pupils.

这所学校因未能鼓励聪明学生而受到非难。

The school has over 850 pupils.

这所小学有850多名学生。