be+动词不定式用法以及几种表示将来时态的辨析

be +动词不定式用法以及几种表示
将来时态的辨析
be +动词不定式（即be + to do sth.）有以下几种含义：
1.表示“将”、“计划”、“安排”。

(意思接近于be going to)
Their daughter is to get married soon.
It was the last film at the cinema，which was to close next day.
注：
was/ were to have done, 表示“本打算”、“本计划”或“本应当”做的事而没有做成或没有发生。

如:
I was to have seen him last Wednesday, but he didn’t come.
We were to have been married last year.
2.表示义务,应该,接近于﹙should,must,ought,have to ﹚
No one is to leave the building. 谁也不得离开这楼房。

You are not to smoke in this room.=You are not supposed to smoke in this room.
You are to be back by 10 o’clock.你必须十点以前回来。

3. 表示“命运”,将来必然要发生的事, 译作“注定……”。

如：
They said goodbye, little knowing they were never to meet
again.
4.用于否定句，表示“禁止”，相当于mustn’t。

例如：
The books in this room are not to be taken outside.这个室内的书籍不
得带出室外。

You are not to smoke in the reading-room.你不可以在阅览室里吸烟。

5. 用于第一人称疑问句，表示征求对方意见。

例如：
Am I to go on with the work?要我继续完成这项工作吗？
What are we to do next?我们下一步该怎么办
6.表示“可以，可能”，相当于may, can。

例如：
The news is to be found in the evening paper.这条消息可以在晚报上见到。

Such people are to be found everywhere.这种人到处都有。

She is nowhere to be found.在哪里也找不着她。

特殊结构：
be to blame(该受责备，对某坏事应负责任)
be to let(待出租)
两种结构中，用不定式的主动形式表示被动含义。

例如：
Which driver is to blame for the accident?这事故是哪个司机的责任？
This house is to let.这房子要出租。

辨析：
1.Wil l①表示未经事先考虑而只是说话时临时作出的决定，②表示说话人认为，相信，希望或假定要发生的事，③也可表示倾向性或规律
性，事物的固有属性或必然趋势。

注：在含有条件状语从句的主从复合句中，主句一般不用be going to，而常用will（第一人称用shall）。

如：
The football match will be put off if it rains tomorrow. 如果明天下雨，足球赛将被推迟举行。

2.Be going to ①表示事先经过考虑，②或有迹象表明某事即将发生或肯定发生，一般带有时间状语，常用于口语。

3.一般现在时表按时刻表或按规定发生的事
4.现在进行时表按计划、安排近期发生的动作(只限于come, go, leave, arrive, start, move, sail, fly, travel, stay等）
5.be about to do 即将常和when引导的时间状语连用(此形式不能与具体时间状语连用）
小试牛刀：
1.The students were told that they ____ at the school gate at 2:00 t he following afternoon.
A. met
B. would meet
C. were to meet
D. were met
2. The house ______ ready today but as there has been a
builders’ strike it is still only half finished.
A. is
B. was to be
C. was
D. was to have been
3.In such dry weather, the flowers will have to be watered if they ___
______.
A. have survived
B. are to survive
C. would survive
D. will survive
4.How _______ I ______ what has become of him?
A. am; to know
B. am; knowing
C. was; to know
D. will; know
5. ______ he _____ tomorrow, I would go to meet him at the station.
A. Were; to come
B. Was; coming
C. Did; come
D. Would; come
答案解析：
1. be to do 表将来, 时态需一致, 用were to meet;
2. 用was表明已经过去, to have been..., 虚拟语气, 与事实相反, 表明本该...却没...;
3. if条件句, 用不定式现在时态be to do表将来;
4. be to do, 表示可能会..., =我怎么知道他的遭遇如何?
5. 虚拟语气, 用were不用was, 即=If he were to come...助动词were 提前，省略if。