五、have to 和must
have to 和must 都作“必须”讲,但用 must时,其强制性来自说话人;而用have to 时,其强制性来自外部环境。例:
Tell him that he must be here by nine. I insist on it. 告诉他,他必须九点钟之前到这里。我坚持要这样。
She sees badly; she has to wear glasses all the time. 她视力很差,不得不整天戴着眼镜。
When a tyre is punctured the driver has to change the wheel. 轮胎被刺穿时,司机就得换车轮。
六、may/ might as well
表示“因为没有更好、更有趣或更有用的事可做,就做某事”:
If you don't like to swim， you stay at home.
A） should as well B） may as well
C） as well D） would as well
（B4，1995.1-60， B对） 如果你不喜欢游泳,也可以留在家里。
七、be+to不定式
这一结构中be可看作半助动词,用来表示:
A） 计划或安排。例:
An investigation is to be made next week.下周将进行调查。
I am to meet him at the airport this afternoon.下午我到机场去接他。
Sir Denis， who is 78， has made it known that much of his collection to the nation.
A）has left B） is to leave C） leaves D） is to be left
（B4， 1996.6-14， D对） 78岁的丹尼斯爵士已经向众人宣布他的许多收藏品将留给国家。
在报纸标题中,be 常常略去以节省篇幅:
(The)Prime Minister (Is) to Make (A) Statement Tomorrow.首相将于明天发表一项声明。
(The) King (Is) to Visit Japan Next Week.国王下周访日。
be 也可用过去时,表示曾经有过的计划;如果这个计划没有实现,不定式用完成式:
The next morning he was to start for the west to make his fortune.他计划第二天早上动身到西部去发财致富。
The students were to have assembled at the auditorium before 9 a.m., but the lecture was cancelled at the last minute.学生们原打算九点前在礼堂集合,可是报告在最后一刻取消了。
The house was to have been ready today but as there has been a builders' strike ,it is still half finished.房子本来计划今天完工,可由于建筑工人罢工,这房子现在只盖了一半。
His mare was to have run in tomorrow's race but he said this morning that she was sick and wouldn't be running after all.他的马本来要参加明天的比赛,可是他今天早上说马病了,不能跑了。
B）表示命令和要求。例:
Nobody is to leave this house without the permission of the police.未经警察允许,任何人不得离开这所房子。
You are to stay here until I return.在我回来之前你得呆在这里。
吩咐注意事项时,to 不定式的被动式是很常见的:
Black skin was to be disguised at all costs.黑皮肤一定要不惜任何代价掩饰起来。
The homework is to be handed in before Friday.家庭作业星期五前交上来。
在表达注意事项的这种结构里,主语和be 都可以省略:
(This medicine is) To be taken four times a day after meals.(此药)一日四次,饭后服用。(写在药瓶上)
(This chemical is) To be kept out of the reach of children.勿让儿童接触(此化学药品)。
C） 表示一种隐藏于未来之中的事,这种事不是事先安排好的。例:
When the boy was born in the log cabin, his mother little thought that he was one day to move into the White House.他母亲在小木屋 生下这男孩时,没有想到他将来有一天会入主白宫。
A decade later his European travels were to be the subject of his first literary book.十年后,他的欧洲之行成了他第一部文学作品的主题。
D） 表示“应该”或“可能”等。例:
Some books are to be tasted, others to be swallowed and some few to be chewed and digested.书有可浅尝者,有可吞食者,少数则须咀嚼消化。
All truths are not to be told.并不是所有真理都可用语言道破。
Such books are nowhere to be found.哪儿也找不到这样的书。
Not a soul was to be seen in the dark street.黑乎乎的街上连个人影也看不见。
E） 在if从句中表示真实条件或虚拟条件。例:
If we are to be at the top of the mountain by twelve o'clock, we must start out now.如果我们想在十二点到达山顶,现在就得出发了。
If you were to attend the banquet， what would you wear?如果你准备出席宴会,穿什么衣服呢?
（本节内容曾经发表在《英语学习》1993年第11期）
