将来的义务 | 英语文法指南 | ef-九游官网下载
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.