【往期回顾】
1. 要是现在他有空的话，他会帮助我们的。
If he had time now, he would help us.
2. 要是她那天晚上在那儿的话，她也许就受伤了。
If she had been there that night, she might have been hurt.
3. 假如我去做这件事，我会用不同的方法。
If I were to do it, I would do it in a different way.
【本期内容】
下面我们继续本周《新概念英语2》第89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 89 A slip of the tongue
People will do anything to see a free show – even if it is a bad one. When the news got round that a comedy show would be presented at our local cinema by the P. and U. Bird Seed Company, we all rushed to see it. We had to queue for hours to get in and there must have been several hundred people present just before the show began. Unfortunately, the show was one of the dullest we have ever seen. Those who failed to get in need not have felt disappointed as many of the artistes who should have appeared did not come. The only funny things we heard that evening came from the advertiser at the beginning of the programme. He was obviously very nervous and for some minutes stood awkwardly before the microphone. As soon as he opened his mouth, everyone burst out laughing. We all know what the poor man should have said, but what he actually said was: 'This is the Poo and Ee Seed Bird Company. Good ladies, evening and gentlemen!'
本课主要是复习第17课、第41课和第65课所学的情态动词must、have to、need、should的用法。
（一）第17课
本课侧重学习的是must的用法，它主要有两种用法：表“必须”；表“一定”。
1、表“必须”
其基本用法为：
sb. must do sth.
其否定表达为：
sb. needn't do sth.
如：
They must drink some water.
They needn't drink any water.
2、表“一定”
此时must表示肯定猜测，当针对不同时间下的状态和动作进行猜测时，其用法都不同。此外，要注意其对应的否定猜测用can't来表示。
1）针对现在时间
（1）状态
其基本用法为：
sb. must be + 名词/数词/形容词/短语等
如：
She must be a teacher.
He must be about fifty.
They must be tired.
The man must be at home now.
（2）动作
其基本用法为：
sb. must be doing sth.
如：
She must be sleeping now.
2）针对过去时间
（1）状态
其基本用法为：
sb. must have been + 名词/数词/形容词/短语等
如：
She must have been a teacher.
He must have been about fifty.
They must have been tired.
The man must have been at home then.
（2）动作
其基本用法为：
sb. must have done / have been doing sth.
如：
She must have been sleeping then. He must have finished the job.
（二）第41课
本课侧重学习的是must、have to和need的用法。
1、must
参考上面第17课里的说明。
2、have to
have to表示“不得不；必须”，在语法形式上其实属于实义动词范畴，所以会受主语人称和数的变化而变化，也有时态的变化。如：
I have to leave here now.
She has to eat two eggs every day.
They had some steak for dinner yesterday.
You will have to read these novels this week.
此外，要注意have to的否定形式可以用作must的否定。如：
The girl must see a doctor at once.
The girl doesn't have to see a doctor at once.
3、need
need被称作半情态动词，因为它既可以用作情态动词，也可以用作实义动词。
当用作情态动词时，need大多用于否定句中，作为must的否定表达，如：
I must give her some help immediately.
I needn't give her any help immediately.
当用作实意动词时，其主要用法有：
She needs some coffee.
He needs to do it now.
The bike needs mending.
You needn't have done that for me.
（三）第65课
本课学习的是must、have to、need、should、ought的用法，但侧重的是should和ought的用法。这两者都表示“应该”，ought要与to连用，语气比should要更强烈一些。其基本用法为：
sb. ought to / should do sth.
如：
She should / ought to get up early to recite the new lesson.
should和ought to也可以用来表达“本该”，即原本应该要去做但没有做。比如：
She should / ought to have attended the meeting, but she missed the first bus.
三、一课一题
根据本课的复习内容，让我们来练一练吧，根据提示把下列句子翻译成英语。
1. 上周凯蒂不得不离开上海。（have to）
2. 她昨天肯定在学校里上课。（must）
3. 你三天前本该把书还给我的。（should）
联系客服
