未來的義務

型態

當我們在談有關未來的義務時,我們可以用兩個要素來構成正式的句型:
依主詞來對 Be 動詞做現在式的詞形變化 + 主要動詞的不定詞

未來的義務,以 to travel 為例
肯定句 否定句 疑問句 否定疑問句
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

在英語的書寫中,我們可以用此句型來論及未來要履行的義務或要求。它的意思跟 must 相似,但有「某事已為我們安排或籌劃」之意,一般並不會用在英語的口語上。

舉例
  • 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.