资源简介

(共39张PPT)
Period 3　Discovering Useful Structures
情态动词和过去将来时
01
要义详析·探究语法
一、情态动词的特点
情态动词本身有一定的词义，通常与动词原形一起构成谓语，表示说话人对某一动作或状态的态度或主观设想。
1．在意义上，情态动词有一定的词义，但不能单独作谓语，需和实义动词或系动词一起作谓语；
2．在形式上，情态动词一般没有人称和数的变化(be able to、have to除外)；
3．在用法上，情态动词与助动词一样，其后需接动词原形，构成谓语动词。
二、情态动词的基本用法

(1)(教材P52)Oliver believes that with a million pound bank note a man could live a month in London.　奥利弗认为一张面值百万英镑的钞票能让一个人在伦敦生活一个月。
(2)(教材P52)May we ask what you're doing in this country and what your plans are
能告诉我们你来这个国家干什么吗？你有什么计划吗？
(3)You must finish your homework this afternoon.
你必须在今天下午完成你的作业。
(4)I promise I will do my best to provide the best service for the Asian Games.
我保证我会尽我所能为亚运会提供最好的服务。
(5)He needn't have gone to hospital, but he went just to reassure himself.
他本不必去医院的，去了只是想让自己放心。
(6)I dare not hand this project over to anyone else.
我不敢将这个项目交给其他任何人负责。
(7)She can't have been to your house; she doesn't know your address.
她不可能去过你家，她不知道你的地址。
句(1)中的could表示“______”；句(2)中的may表示“______”；句(3)中的must表示“______”；句(4)中的will 表示“______”；句(5)中的need表示“_________”；句(6)中的dare表示“______”；句(7)中的can't have done表示对“______”的否定推测。
能力
请求
命令
意愿
必要性
敢于
过去
1．can/could
(1)表示能力，指有能力做某事。could为can的过去式。
(2)表示请求或允许。could比can语气更加委婉，当表示给予允许或同意时通常不用could。
(3)表示推测，意为“可能”，常用于否定句和疑问句中，can't/couldn't意为“不可能”。
(4)表示一时的可能性，意为“有时会”，常用于肯定句中。
2．may/might
(1)表示请求、允许或许可。might在语气上比may更加委婉。以may/might开头的问句在否定回答中要用mustn't。
(2)表示把握不大的推测，意为“可能、也许”，用于肯定句或否定句中，might语气更加不确定。
(3)用于祈使句，表示祝愿。
(4)“may/might as well＋动词原形”是固定结构，意为“不妨……”
根据句意填入适当的情态动词或其否定形式
(1)That _______ be Mary, for she is in hospital.
(2)They often run at high speeds, which ___ put our lives in danger.
(3)___________________ I have a look at your new computer
(4)He _____ be able to solve the problem, but I am not sure. It's a pretty complex issue.
can't
may
Could/May/Might
might
3．shall/should
(1)shall
①用于第一、三人称的疑问句中时，表示征求意见。
②用于第二、三人称的陈述句中时，表示允诺、命令、警告和强制，或表示说话人的决心等。
③在法律、条约、协定等文件中，表示义务、规定等。
(2)should
①表示责任和义务，意为“应该”。
②表示推测，指有一定根据的推测，意为“按道理应该”。
③表示惊讶，意为“竟会、居然”。
4．must
表示现在或将来必须要做某事，多是出于义务、责任或强制命令，指说话人的主观意志。其否定形式为mustn't，意为“一定不要、不准、禁止”。
(1)回答must引导的问句时，如果是否定的回答，要用needn't或don't have to。
(2)must表示“偏要、硬要”，指不愉快的事。
(3)must表示推测，其推测的可能性比较大，意为“一定、必定”，常用于肯定句中。
根据句意填入适当的情态动词或其否定形式
(5)You ______ be Carol. You haven't changed a bit after all these years.
(6)The new law states that people _________ drive after drinking alcohol.
(7)_____ we change the time of the appointment to suit you better
(8)It's strange that he ______ have taken the books without the owner's permission.
must
mustn't
Shall
should
5．will/would
(1)will表示意愿、意志，would表示过去时间的意愿、意志。
(2)表示征求意见或提出请求，主要用于第二人称疑问句中，will和would均可使用，would此时不表示过去，而是表示委婉语气。
(3)will表示某种倾向或习惯性动作，意为“总会、老是”；would表示过去反复发生的动作或过去的一种倾向。
6．need和dare
(1)need表示必要性，意为“需要”；dare表示敢于。need和dare作情态动词时常用于否定句、疑问句或条件句中，无人称和数的变化，疑问句和否定句中不加助动词。
(2)need和dare用作实义动词时，有词形变化；在否定句、疑问句中要加助动词。
根据句意填入适当的情态动词或其否定形式
(9)He _____ go to the river nearby to fish on weekends when he was young.
(10)Now we can do it through face recognition, which really saves time so that we _________ wait in a queue.
(11)You have to go there alone, whether you ____ or not.
(12)If we _____ not go there that day, we couldn't get the beautiful flowers.
would
needn't
will
dared
7．情态动词＋have done
形　式 用　法 例　句
must have done 对过去的肯定推测，意为“过去肯定做了” *It must have rained last night, for the road is quite wet.
昨晚肯定下雨了，因为路面十分潮湿。
can't/couldn't have done 对过去的否定推测，意为“过去不可能做了” *He couldn't have known the decision, for no one told him.
他一定不知道这个决定，因为没人告诉他。
形　式 用　法 例　句
could have done 意为“本来能够做而没做” *You could have made greater progress, but you didn't try your best.
你本能够取得更大的进步，但是你并没有尽全力。
may/might (not) have done 意为“可能(没有)做过” *You may have dropped it when you were shopping in the market.
你或许是在市场买东西的时候把它掉了。
形　式 用　法 例　句
ought to/should have done 意为“本来该做而没做” *You should have come to school if you were really serious about your study.
要是你真的认真对待学习的话，你本应该来上学的。
ought not to/should not have done 意为“本来不该做而做了” I should not have eaten so much cake at the party.
我本不应该在派对上吃那么多蛋糕的。
形　式 用　法 例　句
needn't have done 意为“本来不必做却做了” *You needn't have telephoned him, for he had known the result.
你本不必打电话给他，因为他已经知道结果了。
完成句子
(13)我想不起来了——我当时一定是失去了知觉。
I can't remember any more—I __________________ consciousness.
(14)看看你都做了什么！你本应该更仔细地做这个实验。
Look what you've done! You _______________________ the experiment more carefully.
must have lost
ought to/should have done
(15)你本不必告诉他们我们之间发生了什么事。
You _______________________ them what had happened between us.
(16)你本来能早点通过考试，但你那么粗心，以至于犯这么多错误。
You _____________________ the exam early, but you were so careless as to make so many mistakes.
needn't have told
could have passed
三、过去将来时

(1)(教材P52)Young man, would you step inside a moment, please
小伙子，请进来一下，好吗？
(2)(教材P52)Yes, I was about to go get the letter.
好的，我正要去拿信。
(3)She told her mother that she was leaving for a ball with Mike.
她告诉母亲，她要和迈克一起去参加一个舞会。
以上各句的时态均为过去将来时。句(1)中的过去将来时由“__________”构成；句(2)中的过去将来时由“_________________”构成；句(3)中的过去将来时由“___________”构成。
would do
was about to do
was doing
过去将来时的表示方法：
1．would/should do：表示从过去某一时间来看将要发生的动作或存在的状态。
2．was/were going to do：表示过去将要发生或很有可能发生的动作，常用于口语中，表示意图或者打算等。
3．was/were about to do：常用来表示即将发生的动作，表示“刚要/正要做……”。注意该结构不与任何时间状语连用。
4．was/were to do：表示“曾计划做某事”，也可以表示“命中注定要发生的事”；如果表示“本来计划做某事，动作没实现”，则需用“was/were to have done”。
5．was/were doing：常用动词有start、go、come、leave、see、meet等，表示就过去某一时刻而言即将发生的动作。
完成句子
(1)我原以为他不会参加这个晚会，但是令我惊讶的是，他来了。
I thought he ________________________________, but to my surprise, he came.
(2)周五我们的老师告诉我们，他打算带我们去观看一场辩论赛。
On Friday our teacher told us that ______________________________ a debate competition.
wouldn't attend the evening party
he was going to take us to watch
(3)我们正要离开的时候，孩子们挥舞着双手，感谢我们的好意。
_____________________ when the children waved their hands and thanked us for our kindness.
(4)我刚穿上外套要去看望我的一个朋友。
I had just put on my overcoat and _____________________________．
(5)这个队伍计划在6点出发去比赛，但交通阻塞使他们耽搁了。
_____________________ at 6 o'clock for the game, but the traffic jam delayed them.
We were about to leave
was leaving to visit a friend of mine
The team was to leave
02
课堂微练·即时检验
Ⅰ.单句语法填空
1．He said that if it didn't rain he ___________________(go) to the scene.
2．He was fifty six. In two years he __________ (be) fifty eight.
3．The police still haven't found the lost child，but they're doing all they ___．
could have gone
would be
can
4．—I left my handbag on the train，but luckily someone gave it to a railway official.
—It is beyond belief to get it back！I mean，someone _____ have stolen it.
5．_____ we go there together this Friday afternoon
6．I've realised that playing the game does me too much harm and I ____ change this.
might
Shall
must
7．He finished all the work by himself; in fact, he _____ have asked his friends for help.
8．Our teacher _____ come to the party with us, but we are not sure.
9．The servant said the bus _____________(leave) at five the next morning.
10．He didn't know that the experience was ___________(change) his whole life.
could
might
was leaving
to change
Ⅱ.语法与写作
1．那个测试很容易，他本来应该通过的，但却没有。
It was an easy test and _________________________, but he didn't.
2．你本没必要订票的，因为这几天动物园免费向公众开放。
________________________________, for the zoo is open to the public free of charge these days.
he should have passed it
You needn't have booked the ticket
3．你也可以写一些关于学生日常生活方面的东西，文章的长度应限制在400词左右。
You _______________________ about students' daily life. The length of the article _______________________________________．
4．我仍然记得我快乐的童年，那时我的奶奶常常在周末带我去公园。
I still remember my happy childhood _________________________ ___________________________________．
can also write something
should be limited to 400 words or so
when my grandma would take me to the park at weekends
5．如果我们知道交通状况，我们本来能够早点出发。
If we had known about the traffic, we ________________________．
could have left earlier

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