1)be going to +v 在口语中广泛使用,表示准备做或将发生的事情。例如:
I’m going to buy a house when we’ve saved enough money.
2)be to +v 表示计划安排要做的事,具有“必要”的强制性意义。例如:
I am to play tennis this afternoon.
3)be about to +v 表示即将发生的事情。例如:
He was about to start.
4)be due to +v 表示预先确定了的事, 必定发生的事。例如:
The train is due to depart in ten minutes.
5) be on the point/verge of +v – ing 强调即将发生的某种事态。例如:
The baby was on the point of crying when her mother finally came home.