exercise 可以是动词

exercise 可以是动词“锻炼”，如He exercises every day. 此时，exercises 是exercise 的单三形式。

exercise 也可以是名词。

（1）“练习”，“操”可数名词如There are many exercises in the book.
We should do eye exercises.
（2）“锻炼”，不可数名词如Let's take exercise.
追问
早操或课间操是要exercise还是exercises呢
回答
早操：morning exercises..eyes exercises
2.Take more______ ,please don't always to _____at your desk. (exercise) exercise作名词：1、当exercise表“体格锻炼，运动；运用”时，为不可数名词；Walking is good exercise.散步是很好的运动。

2、当表“体操；（一种）运动；练习；实习；习题；练习（教材）”时，为可数名词；Physical exercises 体育；do morning exercises 做早操；exercises for the violin 小提琴练习；an exercise in grammar 语法练习exercise作动词：exercise是动词原型，exercises是单三形式。

You don't exercise enough.你锻炼不够。