人教版新课标必修三 unit2 Healthy eating Grammar（共20张PPT）

(共20张PPT)
B3 UNIT2
Healthy eating
Grammar
情态动词（2）

一、教材原句
1．(教材P10)By now his restaurant ___be full of people.But not today!
2．(教材P10)Something terrible ____ have happened if Li Chang was not coming to eat in his restaurant as he always did.
3．(教材P14)____I ask what you were doing in my restaurant the other day?
4．(教材P15)Perhaps we ____ combine our ideas and provide a balanced menu with food full of energy and fibre.
答案1 ought to 2must3May4ought to

二、情态动词的概述
1.概念：情态动词是表示说话人的语气或情绪的词，如可能、意愿、猜测、义务、需要等。2.特征：
(1)．有一定的词义，但不能单独作谓语，后面接动词原形。
(2)．没有人称和数的变化(have to除外)。
(3)．多数情态动词都有过去式，如can—could，may—might，will—would，dare—dared等。情态动词的“时态”并不是区分时间的主要标志。很多情况下，情态动词的原形和过去式都可用于多种时态。

三、情态动词的用法

1．ought to
(1)表示出于义务、责任、道义等方面的要求而该做某事。
I feel that we ought to accept his advice.
我觉得我们应该接受他的建议。
To be a popular student，we ought to be strict with ourselves.要成为一名受欢迎的学生，我们应该严格要求自己。





(2)ought to的否定式是在ought后加not，疑问式是将ought提前。
You ought not to play tricks on the disabled.
你不应该捉弄残障人士。
—Ought I to set off tomorrow?
——我明天该动身吗？
—Yes，you ought to.
——对，你应该。



2．Need
need作情态动词时，后跟动词原形，表示“需要，有必要”，无人称和数的变化，多用于否定句、疑问句或条件句中。
I wonder if we need take a sleeping bag.
我想知道我们是否需要带睡袋。
There’s plenty of time.You needn’t drive so fast.
时间很充足，你不必开得这么快。





特别提醒：由need引导的一般疑问句的肯定回答常用must或have to，否定回答常用needn’t。
—Need I answer the question?
——我需要回答那个问题吗？
—Yes，you must./Yes，you have to.
——是的，你必须回答。/是的，你得回答。
/—No，you needn’t.
——不，不必了。
?


3．have to/don’t have to/mustn’t
(1)have to表示客观上的必要性，意为“不得不；只好”。它有多种时态变化形式以及人称和数的变化，其疑问句式和否定句式由助动词do构成。
He is in debt，so he has to work hard day and night.
他负债累累，所以他不得不夜以继日地工作。
If you earn more than ￡5,000，you will have to pay tax.
如果你收入超过5000英镑，就得交税了。


5
(2)have to的否定式don’t have to表示没有义务或没有必要做某事，意为“不必”，相当于needn’t。常可以回答以must开头的疑问句。而must的否定式mustn’t表示“禁止，不许”。
You are old enough，so you don’t have to get permission from him.
你足够大了，因此不必得到他的许可。
You don’t have to finish the work now.


你现在没有必要完成这项工作。
—Must we dress up to go to the party today?
——今天我们必须盛装参加晚会吗？
—No，you don’t have to/you needn’t.
——不，你们不必。
(肯定回答为：Yes，you must.)



4．情态动词＋have done
(1)must have done表示对过去发生的动作或状态进行推测，语气比较肯定，通常只用于肯定句。
From what you said，she must have told you all about it.
从你所说的来看，她一定把一切都告诉你了。
(2)may (might) have done表示对已发生的动作或存在的状态进行不肯定的推测，might的语气比may弱。主要用于肯定句或否定句。
The boy might have known the truth，but I am not quite sure.
那个男孩(当时)也许知道了真相，但我不是很确定。



(3)can(could) have done表示对过去的某种情况的怀疑或不确定，一般用于否定句和疑问句，could的语气较can弱。could have done还可表示过去本来能做的事情而没做。
He can’t have left.His bag is still in the room.
他绝不可能走了，他的包还在屋里呢。
In my view，this accident could have been prevented.
依我看，这次事故本来是可以避免的。


(4)ought to (should) have done表示过去本应该做某事但没做，其否定式表示过去不该做某事但做了。
They ought to have been more careful.
他们本该更小心些。
You should have told me earlier or I might have gone with them.
你应该早点告诉我，不然的话我就会和他们一起去了。
(5)needn’t have done表示过去做了不必做的事情。
He needn’t have gone there yesterday.
他昨天其实不必去那儿的。



四、巩固训练
选词填空
can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
1．You __________ go there alone; it’s too dangerous.
答案：　mustn’t
2. It’s so near; we __________ have taken a taxi.
答案：　shouldn’t
3．You __________________ have spent so much time playing computer games.
答案：　oughtn’t to





选词填空:can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
4．—Shall I leave the room so that you two can talk?
—No，you __________.
答案：　needn’t
5．He __________ have missed the train; he arrived at the train station two hours early.
答案：　can’t
6. We’ll be very glad if you __ join us in going camping.
答案：　can



选词填空:can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
7．They ______________ stay in the office last night because of the snowstorm.
答案：　had to
8．We __________ have helped him; in that case，he would have been able to finish the work.
答案：　should
9. From what you said，she ____ have told you all about it.
答案：　must



选词填空:can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
10．Immediate actions _______be taken，like stopping cutting down trees, to better the environment.
答案：　ought to
11．She is really angry.You __________ have spoken to her in such an unfriendly way just now.
答案：　oughtn’t to
12．—Shall I tell my friend Tom about it?
—No，you _________.I’ve already told him yesterday.
答案：　needn’t


选词填空:can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
13. You’re John’s good friend，so you __________ know what he likes to do at the weekend.
答案：　must
14. My mother’s birthday is coming.What __________ I buy for her?
答案：　shall
15．When I was at university，I __________ go to the bookstore on weekends.
答案：　would


选词填空:can’t；mustn’t；shouldn’t；needn’t；had to；oughtn’t to；ought to；must；should；can ;shall
16．Mr Zhang__________ have gone to America，for I saw him just now.
答案：　couldn’t
17．She is a shy girl，so she __________ be a little nervous in such a serious situation.
答案：　might
18．We __________ have hurried; you see，everything is ready and there is much time left.
答案：　needn’t


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