将来的义务

型态

当我们在谈有关将来的义务时,可以用两个要素来构成正式的句型:
依主词来对 Be 动词做现在式的词形变化 + 主要动词的不定词

未来的义务,以 to travel 为例
肯定句 否定句 疑问句 否定疑问句
I am to travel. I am not to travel. Am I to travel? Am I not to travel?
You are to travel. You are not to travel. Are you to travel? Aren't you to travel?
He is to travel. He is not to travel. Is he to travel? Isn't he to travel?
It is to travel. It is not to travel. Is it to travel? Isn't it to travel?
We are to travel. We are not to travel. Are we to travel? Aren't we to travel?
They are to travel. They are not to travel. Are they to travel? Aren't they to travel?

作用

在英语的书写中,我们可以用此句型来论及我们未来要履行的义务或要求。它的意思跟 must 相似,但有「某事已为我们安排或筹划」之意,一般并不会用在英语的口语上。

举例
  • You are to leave this room at once, and you are to travel by train to London.
  • In London you are to pick up your ticket from Mr Smith, and you are to fly to your destination alone.
  • When you arrive, you are to meet our agent, Mr X, who will give you further information.
  • You are to destroy this message now.