I.词语辨析：
1. be to do / be about to do / will do / be going to do
be to do：是一种将来时，含有说话者的“命令、警告、决心”等的口气，还可以表示：“(后来)注定会……”的意思。
e.g. You are to hand in your homework this afternoon.
We are to finish the task by Friday.
She is to be a world known actress.
be about to do：解释为“就要/正要做……”，是一个即将发生的（将来）动作，常与when引导的时间状语从句连用，构成句式：be about to do … when …。
e.g. We were about to go out when it began to rain.
I was about to call her when the phone rang.
will do：是最常用、最普通的一种将来时，不带有感情色彩。在指1）未经仔细思考2）自然变化或某种规律性的情况时，要用will表示。
