自由体操(floor exercise）exercise后面加不加S

doing morning exercise加不加S exercise 眼保健操的英语表达eye exercise exercise加不加s to do some exercise 为什么exercise 后面不加S啊 she ofen exercise.exercise加s吗? exercise什么时候加s exercise 什么时候要加“s”? do exercise 加s么? exercise什么时候家s,举例说明 do exercise什么时候加s? It's good exercise.中exercise做什么语, 为什么 favorite exercise中exercise不用加s