有些结构可以表示过去某时打算要做的事或预计要发生的事，如：

1）过去进行时（仅限于come, go, leave这类动词）：

He was busy packing, for he was leaving that night. 他忙着收拾行李，因为那晚他就要走了。

She told me she was going to Boston. 她告诉我她准备去波士顿。

2）was going to:

She said she was going to come early. 她说她一早就来。

When I arrived, the train was just going to start. 我到时火车正要开出。

3）be about to（表示“就要”、“即将”发生某事）:

He was about to go out when the phone rang. 他正要出去时电话铃响了。

I was just about to explain when shen interrupted me. 我正要解释，她打断了我的话。

4）be due to（表示“定于”）：

He was due to speak that night. 他定于那天晚上发言呢。

Mary was due to leave at 2 o'clock. 玛丽定于两点出发。