be to + 不定式”表示将来时间
They were to celebrate their fifteenth wedding anniversary. (Passage A, Unit 3)
此句中的were to celebrate (即be to + 不定式) 表示按计划或安排将要发生的事情。
英语中有很多表示将来时间的手段，“be to + 不定式”是其中之一。这一结构常用来表示下列意义：
1. 表示按计划或安排将要发生的动作或事情。例如：
I am to have tea with Mary this afternoon.
They are to get married next month.
There is to be a big party on New Year’s Day.
The factory is to turn out 20,000 cars next year.
Where are we to live when we arrive in the U. S.?
The chairman is to speak on television tonight.
这种情况下动词be也可用过去式，表示过去将来时间。例如：
The meeting was to be held the following week.
There was to be a dinner party when the guests arrived.
另一结构“be going to + 不定式”也可用来表示按计划或安排将要发生的动作或事情，且常可与“be to + 不定式”换用。例如：
We are going to / are to have the final exam next week.
There is going to / is to be a class meeting at 2 o’clock this afternoon.
但是，需提示学生注意的是，“be to + 不定式”的结构通常只表示受人意志控制的将来动作。如要表达不受人意志控制的将来动作，则必须用“be going to + 不定式”，而不能用“be to + 不定式”。例如：
It’s going to rain.
[误] It’s to rain.
She is going to become fatter.
[误] She is to become fatter.
2. 表示命令或禁止（意义接近must / have to）。例如：
You are to be back by nine o’clock.
You are to stay here all the time.
You are to follow all the rules.
You are to wait until I come back.
You are not to stand in this place.
This classroom is not to be used this afternoon.
You are not to wake up the baby now.
This kind of game is not to be played here.
3. 表示说话人认为注定要发生的动作或事情。例如：
He is to fail sooner or later.
Better days are soon to follow.
Harry and Jane are to have a happy family.
Bad people are to come to no good end.
4. 表示说话人认为应该做的事情（意义接近should / ought to）。例如：
Students are to remember all these words.
We are to help each other.
What’s to be done?
He is to let us know everything.
Mistakes like this are to be avoided.
Such questions are to be asked in the class discussion.
5. 表示能够，可能（常用于否定句和疑问句，意义接近can / may）。例如：
Nobody was to be seen in the classroom.
Not a useful book is to be found in this library.
How are you to describe her in that way?
How are you to believe such a story?
6. 表示想要，打算（常用于条件分句）。例如：
If you are to speak English well, you must practice hard.
If we are to finish the work on time, we’ll have to be quick.
If he is to earn much money, he has to work very hard.
You’ll have to eat less and do more exercises if you are to lose weight.
be to + 不定式”表示将来时间 语法讲解
»
