高中英语人教版必修三课件：Unit 2 Section ⅢGrammar——情态动词(Ⅱ)

5. You needn't buy (not buy) a gift，but you can if you want to. 6. Look! The road is wet.It must have rained (rain) last night. 7. Bob ought not to speak (not speak) to his mother like that. 8．You must come (come) here on time，or you'll be fined next time. 9．Hurry up! We ought to/should go (go) to school right away. 10．Her eyes are red.She must have been (be) crying.
3．“应该”，表示推测。可与 should 换用。 Mary ought to be here soon. 玛丽应该很快就来了。 This is where the oil ought to/should be. 这里应该就是石油存在的地方。
[即时训练 1] 用 ought to 补全句子
①下次过马路时，你应该更小心些。 You ought to be more careful when you cross the road next time. ②你不该责备他。
[考点警示] have to，must (1)两者都可意为“必须，应该”，但 have to 表示客观的需要，而 must 表示说话人主观上的看法，即主观上的必要。 (2)have to 有人称、数和时态的变化，而 must 只有一种形式。 He had to look after his sister yesterday. 昨天他不得不照顾他的妹妹。
can/could have done
1.过去可能(表推测) 2．本能做而未做(表虚拟)
should/ought to have done
本该做而未做
may/might have done
must have done needn't have done
1.过去也许做了(表推测) 2．本可能做而未做(表虚拟) 一定已经做了 本不必做而做了
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。 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块去了。 They could have sent up the satellite successfully. 他们本来有能力成功发射这颗卫星的。
Unit 2 Healthy eating Section Ⅲ Grammar——情态动词(Ⅱ)
[语 境 自 主 领 悟]
先观察原句
后自主感悟
①By now his restaurant ought to be full 1.以上句子中，句①④⑤⑥中的黑体词都
of people.
是情态动词，而句②③中的黑体词是实义
The house needs/wants/requires repairing/to be repaired. 这所房子需要修葺。
[即时训练 3] 完成句子 ①我的房间很乱，但今晚出去之前我不需要打扫，我会早晨打扫的。 My room is in a mess，but I needn't clean it before I go out tonight.I can do it in the morning.
(应
当限制在 400 词左右)．
3．The last important thing you should remember (你应当记住的是)is that
you have to send the article to me before June 28. 4．George can't have gone (不可能走) too far.His coffee is still warm.
②——我需要留下来帮他们吗？ ——是的，你必须留下来。不，你不必。 — Need I stay to help them? —Yes， you must．/No， you needn't ．
四、情态动词＋have done
“情态动词＋have done”表示对过去事情的推测。各情态动词的这种具
体用法如下表：
2．“应该”，表示劝告、建议或命令。should 和 ought to 可通用，但在 疑问句中常用 should。ought to 的否定式为 oughtn't to 或 ought not to。
You ought to balance career and family. 你应该平衡好事业与家庭之间的关系。 Should I open the window? 我可以打开窗户吗？
You ought to/should have been more careful. 你本应该更小心一些的。 You needn't have told them about it. 你本来没有必要告诉他们那件事。
[即时训练 4]完成句子 ①我从未玩得更开心过——这是完美的一天。 I couldn't have enjoyed myself more—it was a perfect day. ②他们本应该在午饭时间就到达的，但是他们的航班被耽搁了。 They should have arrived at lunchtime but their flight was delayed.
[即时训练 2] 完成句子(每空 1 词) ①他没有钱，只好放弃这个计划。 He had no money，so he had to give up this plan. ②你千万不能告诉他这个秘密。 You mustn't tell him the secret. (3)——我们必须今天下午交作业吗？ ——不，你不必。 —Must we hand in our homework this afternoon? —No，you don't have to．
if Li Chang was not coming to eat in his
不”。
restaurant as he always did.
[语 法 精 要 点 拨]
一、ought to 的用法 1．“应该”，表示责任或义务。用于表示按道理应当，常指客观的义务 或责任，大多数情况下可用 should 代替，但比 should 语气重。 You ought to study harder than your brother. 你应该比你哥哥更努力学习。 I should help her because she is in trouble. 她有困难了，我应该帮助她。
—Need I hand in my paper now? —Yes，you must./No，you needn't. ——我现在需要交上论文吗？ ——是的，你必须。/不，你不需要。
(2)作为实义动词，同其他实义动词一样，可用于各种句式，有时态、人 称和数的变化，构成否定句和疑问句时要借助于助动词 do。
②Does your father need any help?
动词。
③What do we need to take for the picnic?
2．以上各句中的情态动词后都接动词原
④There is enough time.You needn't hurry. 形。其中句⑥中 must have happened 的意
三、need 的用法 (1)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。 You needn't go there now.你不必现在去那儿。 Need I go there now？我现在需要去那儿吗？
[考点警示] 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。
Ⅱ.完成句子
1．I have just found that I have to attend an important class meeting
(我必须参加一个重要的班会) that afternoon.
2．The length of the article should be limited to 400 words or so
7．—Sorry，Mum！I failed the job interview again. —Oh，it's too bad.You should have made full preparations (本应该做 充足的准备)．
⑤His mother is ill.He has to stay at home 思是“一定已经发生了”。
to look after her. ⑥Something terrible
3．上述句子中 ought to 意为“应该”； must have happened
need 意为“需要”；has to 意为“不得
You oughtn't/ought not to scold
him.
③——我应该明天动身吗？
——是的，你应该。
— Ought I to leave tomorrow?
—Yes， you ought to ．
二、have to 的用法 have to 意为“不得不”，有时态、人称和数的变化，其否定形式和疑问 形式需要借助于助动词 do。 It was raining outside；we had to stay at home. 外面下雨了，我们不得不待在家里。