将来失态的区别it will do sth 和 it will be to do sth 有啥不同?以及I will d

I will be doing sth 将来进行时,表示将来某个时间点正在做某事,一般会跟将来某个具体时间,比如 I will be doing my homework at 7o'clock tomorrow evening.
I am going to do sth 表示计划将来做某事,这件事已经计划好了,比如I am going to visit London next week.
I am to do,be to do结构 也是表示计划将来做某事,但be to do结构比be going to do 正式,日常用语中很少用,多用于正式场合,比如President Obama is to attend the UN conference next Monday.
I am about to do 意思是 马上做某事,立刻做某事,该结构不能接时间状语,不能说 I am about to do sth at 5o'clock.
I will do sth 一般将来时,表示将来做某事,用的比较广,也可以表示马上去做,比如 Would you like some sugar?I'll get it for you.
更详细的区别可以参见http://hi.baidu.com/%B9%C7%D3%F1%BA%AE%B1%F9/blog/item/bc03724fb65054c1d1c86a01.html

i will do sth 我将要做某事 （在将来某一时刻）＝i am going to do sth
i will be doing sth 我将会在某一时间正在做某事
i am about to do sth 基本上等同于i will do sth 但是时间上有些不同 强调时间的靠近 即 紧接着我会做某事
前两个 不清楚 好像没有这两个啊...