exercise与exercises有什么区别

exercise与exercises有什么区别 Exercise和exercises什么区别? do exercise和do exercises有什么区别? 英语：do exercise 和do exercises 有什么区别? exercise 与exercises 的区别及用法 exercise与exercises区别,两者联系,要怎么用? exercise和exercises的区别? do exercise 和do exercises的区别 exercise&exercises take exercise和take exercises的区别 do exercise和do exercises的区别 exercise和exercises在这里的区别英语 more exercise 和 more exercises的区别 速求!