I'll be missing you 里有什么语法?

I'll be missing you 里有什么语法?
为什么要用BE?有什么相关的语法.请指教一下.

will be doing sth=will do sth
将来进行时
1.概念：将来进行时主要表示将来某一时间正在进行的动作,或表示要在将来某一时间开始,并继续下去的动作.常用来表示礼貌的询问、请求等.如：
This time next day they will be sitting in the cinema.
What will you be doing at six tomorrow evening?
He won’t be coming to the party.
I’ll be meeting him tomorrow/next year/some/time.
2）常用的时间状语
Soon,tomorrow,this evening,on Sunday,by this time,tomorrow,in two days,tomorrow evening
By this time tomorrow,I'll be lying on the beach.
2.将来进行时的形式：
将来进行时由“动词be的将来时+现在分词”构成,具体形式见下表：
人称 单数 复数
第一人称 I shall/will be leaving.We shall/will be leaving.
第二人称 You will be leaving.You will be leaving.
第三人称 He/She/It will be leaving.They will be leaving.
3.将来进行时的基本用法：将来进行时表示在将来某一时间内正在进行的动作.将来进行时有很强的推测性,因此人们往往在以下几种场合中使用它：
（1）表示将来某一时间正在进行的动作,一般带状语.如：
What will you be doing at this time next Monday?
When he comes to my house tomorrow,I will be writing the report.
(2)表示现在正在进行的动作,但这个动作会延续到将来.如：
I wonder if it will still be raining this afternoon.
I think that she will be working on this experiment until next morning.
(3)表示预定的将来动作或对将来的预测.如：
Tomorrow I will be flying to Bombay.
After you take the medicine,you will be feeling much better.
(4)表示委婉的请求
When shall we be meeting again.
(5)表示原因
Please come torrow afternoontorrow morning,I'll be having a meeting.
(6)表示结果
Stop the child or he will be falling over.
(7)表示对将来的打算（区别于对将来的预测）
My duties will end in July ,and I'll be returning to ShangHai.