一课一题一语法：新概念英语第2册第65课
【往期回顾】
【本期内容】
下面我们继续本周《新概念英语2》第65课的重点句型或语法的分享。先来读一读课文：
一、课文原文
Lesson 65 Jumbo versus the police
Last Christmas, the circus owner, Jimmy Gates, decided to take some presents to a children's hospital. Dressed up as Father Christmas and accompanied by a 'guard of honour' of six pretty girls, he set off down the main street of the city riding a baby elephant called Jumbo. He should have known that the police would never allow this sort of thing. A policeman approached Jimmy and told him he ought to have gone along a side street as Jumbo was holding up the traffic. Though Jimmy agreed to go at once, Jumbo refused to move. Fifteen policemen had to push very hard to get him off the main street. The police had a difficult time, but they were most amused. 'Jumbo must weigh a few tons,' said a policeman afterwards, 'so it was fortunate that we didn't have to carry him. Of course, we should arrest him, but as he has a good record, we shall let him off this time.'
大家可以从下面购买《新概念英语》第二册的官方教材：
本课主要学习情态动词must、should、ought to的用法。
（一）must
must主要有两个用法，一是表“必须”，二是表“一定”。
当must表“必须”时，要注意其否定形式为needn't，也可以用don't have to。此外，也要注意needn't（不必）与mustn't（不能）的区别。如：
We must take positive steps to deal with the problem. 我们必须采取积极措施处理这个问题。 We needn't / don't have to take positive steps to deal with the problem. 我们不必采取积极措施处理这个问题。 One mustn't be carried away by one's successes. 在胜利面前不要忘乎所以。
当must表“一定”时，是一种肯定猜测，要注意其否定表达为can't。此外，要注意其对不同时间的猜测时的用法。如：
It must be hard for her, bringing up four children on her own.
她一个人抚养四个孩子一定很艰难。
I think we must have taken a wrong turning somewhere.
我觉得我们一定是在什么地方拐错了路。
（二）should与ought to
两者都表示“应该”，ought to的语气更强。此外，要注意should / ought to have done的虚拟语气用法，表示“本该”。如：
You should not go out in the heat of the day. 你不应该在天最热的时候外出。 We should have had a proper discussion before voting. 我们本应在表决之前好好讨论一下才是。 Maybe we ought to go down to the library and check it out 或许我们应该去趟图书馆，查个明白。 He ought to have reached the house some time ago. 他应该早就到房子那儿了。
三、一课一题
根据本课的重要语法点，让我们来练一练吧，请选择正确的选项。
The work must _____ within two weeks. We should not _____ the past three days.
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