be+動詞不定式即be+to do sth
1表示按計劃或安排要做的事
When are you to leave for home?你什麼時候回家？
She is to be married next month.她將於下個月結婚。
The queen is to visit Japan in a week’s time.女王將於一周後訪問日本。
注意：這種結構也可使用於過去時的句子。Was/were to do sth表示曾經計劃要做的事，但不表明計劃是否被執行，或表示「命中注定要發生的事），而非計劃;was/were to have done sth表示未曾實現的計劃。如：
I felt nervous because I was soon to leave home for the first time.
我感到很緊張，因為我很快就要第一次離開家了。
2表示「應該」，相當於should，ought to 。如：
You are to report to the police.你應該報警。
3 表示「必須」，相當於must, have to。如
You are to do your homework before you watch TV.看電視之前你得先做完作業。
4 表示「想，打算」，相當於intend, want。 如：
If we are to be there before ten, we』ll have to go now.
如果我們要在十點前到，我們現在就得走。
5 用於第一人稱疑問句，表示徵求對方意見。如：
What are we to do next?我們下一步該怎麼辦？
6用於否定句，表示禁止，相當於mustn’t。 如：
You are not to smoke in the reading room.你不可以在閱覽室吸菸。
7 表示「可以，可能」，相當於may,can。如：
The news is to be found in the evening paper.這條消息可以在晚報上見到。
8 were to do sth用於 if或even if/though 從句中，表示對未來假設。如
If I were to tell you that I passed the exam, would you believe me?
要是我告訴你我及格了，你會相信嗎？
9 be to blame（該受責備，對某壞事應負責任）和be to let（待出租）兩種結構中，用不定式的主動形式表示被動含義。如：
Which driver is to blame for the accident?這事故是哪個司機的責任？
10 be going to
1）表示將要發生的事情或打算最近要進行的動作。如：
It is going to rain soon.快要下雨了。
2）在含有條件狀語從句的主從複合句中，主句一般不用be going to，而常用will（第一人稱用shall）。如
The football match will be put off if it rains tomorrow.如果明天下雨，足球賽將被推遲舉行。
11 be about to
1）表示即將發生的動作，在時間上指最近的將來。
The new school year is about to begin. 新學期開學在即。
2）在含有be about to的句子中，不能再加時間狀語。如：
錯誤 The medical team is about to start immediately.
正確 The medical team is about to start.醫療隊就要出發了。
習題
1 I ____ to bed when there was a knock at the door.
A went B is to be sent C was to go D. was about to go
2 -___we ____ again next week? -Yes, le’s make it next Wednesday.
A are, to meet B. Shall, be to meet C. Will, meet D. Are, meeting
3 As students, we _____.
A. won’t smoke. B. are not to smoke C aren’t smoking D don’t smoke
4 Who do you think ____ for the failure of their marriage.
A to blame B.to be blame C.is to blame D. is to be blamed
5 Look at these clouds. _________,
A It’s going to rain B. It’s raining C It is to rain D. It can rain
6 Neither you nor he ______ to the front.
A are to be sent B. is to be sent C. have to be sent D.is to be sent
7 If the sun ______ tomorrow, what would we do?
A were not to raise B. does not rise C. would not rise D. were not to rise
8 -We just saw John at the bookstore.
-That’s strange examination _____ early July.
A will come B. was to come C. is coming D. is to come
e 9 The final examination _______ early July.
A. is to be held B. is to be taken place
B. is going to hold D. will be to take place
10 A new hospital was to____ in this district, but the money wasn’t collected yet.
A have been built B. be built C. built D have built
答案1 D 2 A 3B 4 C 5 A 6B 7D 8B 9A 10A