I will be back 和I will back.为什么要加be?

I will be back 和I will back.为什么要加be? “I will be back! 我会回来的英语是I will be back,为什么不是I will back?back不是动词吗,为什么要加be I will be back,from i will be back歌词 i will be back soon i will be coming back I will be back,We will be back i will be back.i will back 有什么区别 i will be come back 和I will be back是 一个意思吧? i will be right back和 i will be back right有什么区别? i will be right back和i will be back soon有什么区别?