(1) about to do 意为“不久就要……” (going to do very soon) 或“正要……”(just going to do)。

• Don't go out now — we are about to have lunch.
  不要出去了——我们就要吃午饭了。
• I was about to go to bed when there was a knock at the door.
  我正要去睡觉，这时有人敲门。

(2) 在美式英语中，“not about to do”表示“不愿”(unwilling to do)或“不打算”(not going to do) 之意。

• I'm not about to pay 50 dollars for a dress like that.
  我可不愿为那样一套衣服付50美元。
• A: Will you go with them? 你要跟他们一起去吗？
  B: I'm not about to . 我不打算去。