1、现在完成时与情态动词教学内容一、现在完成时的构成：1. 现在完成时由助动词have/has+动词的过去分词构成。若主语为三人称单数，则用has+过去分词；若主语为非单三，则用have+过去分词。have, has在名词或代词后的缩写为ve和s。如：I have=Ive, she has=shes； have not和has not的缩写形式分别是havent, hasnt。2. 现以动词wait为例，列表说明现在完成时的构成。二、 现在完成时的用法：（1）表示动作已经完成，但后果或影响仍在。常与already, just, yet等副词连用。Twenty people have already
2、 left.二十人已经离职。He has not come yet. 他还没有来。 Theyve just arrived. 他们刚刚到达。（2）表示过去发生的动作一直持续到现在。常与for或since引导的一段时间状语连用。He has lived here for three years.他在此住了三年了。I have been here since 1976.自从1976年我就一直在这里。三、 现在完成时与一般过去时的区别：现在完成时与一般过去时都表示动作已经发生，但不同点在于：（1）现在完成时强调这一动作与现在的关系，即对现在产生的结果、影响等，而一般过去时只表示过去的事实，不表示和现
3、在的关系。He has learned French for three years.他学法语已三年了。He learned French for three years.他曾学过三年法语。Who has taken my bag? I coundt find it.谁拿走了我的包？我找不着了！He cleaned the house yesterday.他昨天打扫过房间。The room is clean, for he has cleaned it already.房间很干净，因为他已经打扫过了。（2）现在完成时不可与表示过去的时间副词连用，而一般过去时则可以。He has done so
4、me washing yesterday.（）He did some washing yesterday.（ ） 他昨天洗衣服了。四、现在完成时与一般现在时的区别：在遇到一般现在时与现在完成时在意义上有相似情况时，现在完成时比较强调一个动作从过去到现在的演变过程，语言比较规范，语气也比较正式；而一般现在时着重能力、习惯、心理状态或现在存在的状态等。试看以下例子： 1. (a)中的come from是一个习惯说法，意思是指他出生在加拿大。 (b)中的come from不是习惯说法，全句的意思是他是从加拿大来的，该句丝毫没有出生在加拿大的含义。(b)句使用现在完成时是因为：该动作已经发生完成，但与
5、现在仍有关系，说话者的言下之意可能是Maybe he can speak English或者是So he can tell you something about Canada.。2. (a)使用的是一般现在时，表示的是不仅刚才唱得好，而且具有演唱才能。全句的意思是简唱得很好。(b)使用的是现在完成时，仅表示刚完成的一次动作，不指平常唱的如何，而是强调对现在的影响。也许说话者的言下之意是Now she can pass the music test.3. (a)和(b)都表示他（刚才）说什么？但(a)似乎更普遍，(b)则用得较少。一般现在时表示刚刚过去的情况并不罕见，这是由于说话人着重现在的结
6、果的缘故。(b)则强调过渡，时间性较强。4. 这两句话都比较常用，意义上也无甚差异。如细加区别，(a)比较着重现在的结果，语气比较轻松，可以说是一种现成的说法；(b)则强调从过去到现在的过程，语气比较认真，结构也比较正式。五、完成时态中瞬间动词的处理根据英语习惯，现在完成时的肯定句，其谓语动词如果是瞬间动词，如come, leave, go, begin, join, borrow, lend, buy等，则不可与for, how long等表示时间段的状语连用的。为了防止出现违背这一习惯的错误，一般采用：1. 用ago代替for，并将句子的时态改为一般过去时。eg. The train le
7、ft ten minutes ago. 火车十分钟前开走了。= The train has been away for ten minutes. 火车已经离开十分钟了。He arrived here two weeks ago. 他两周前到这儿的。= He has been here for two weeks.他已经来这里两周了。2. 使用It is+since+过去时态的句子。eg. It is a very long time since we met last time. 自从上次见面以来，我们很久未见了。= We havent seen each other for a long t
8、ime since we met last time. It is thirty years since they married. 他们结婚有30年了。= They have been married for thirty years.3.用持续性动词或状态动词代替瞬间动词。以下是常见的瞬间动词与其对应的持续性动词：become - be borrow - keep leave - be away lose/sell - be gone buy - have marry- be married fall asleep- be asleep wake- be awake open-be ope
9、n die-be dead catch a cold -have a cold fall ill -be ill start/begin -be on finish/end -be over join -be in return -be back come here/get here/arrive here -be here (there )练习:1、Both his parents look sad . Maybe they _whats happened to him . . knew . have known . must know .will know 2、He has _ been
10、to Shanghai , has he ? . already .never .ever . still 3、Have you met Mr Li _？ . just . ago .before . a moment ago 4、The famous writer _ one new book in the past two year . . is writing .was writing .wrote .has written 5、Our country _ a lot so far . Yes . I hope it will be even _ . . has changed ; we
11、ll . changed ; good . has changed ; better . changed ; better 6、Zhao Lan _already _in this school for two years . . was ; studying . will ; study . has ; studied . are ; studying 7、We _ Xiao Li since she was a little girl . . know . had known . have known . knew 8、Harry Potter is a very nice film .I
12、_ it twice . . will see . have seen . saw .see 9、These farmers have been to the United States . Really ? When _ there ? . will they go . did they go . do they go . have they gone 10、_ you _ your homework yet ? Yes . I _ it a moment ago . . Did ; do ; finished . Have ; done ; finished . Have ; done ;
13、 have finished . will ; do ; finish 六、情态动词功能与用法功能助动词主要有两类：基本助动词和情态助动词。基本助动词有三个：do, have和be；情态助动词基本的有十四个：may, might; can, could; will, would; shall, should; must, need, dare, used to, ought to.had better 上述两类助动词的共同特征是，在协助主动词构成限定动词词组时，具有作用词的功能： 1） 构成否定式： He didnt go and neither did she. 他没去，她也没去。 The
14、meeting might not start until 5 oclock. 会议可能直到五点才开始。 2） 构成疑问式或附加疑问式： Must you leave right now? 你一定要马上离开吗？ You have been learning French for 5 years, havent you? 你已经学了五年法语，不是吗？ 3） 构成修辞倒装： Nowhere can he obtain any information about his sister. 他无处得到他姐姐的任何消息。 Hardly had he arrived when she started com
15、plaining. 他刚到，她就开始抱怨起来。 4） 代替限定动词词组： A: Who can solve this crossword puzzle? B: Tom can. A: Shall I write to him? B: Yes, do. 用法 can (could), may (might)的用法can (could) 表示说话人能,可以,同意,准许,以及客观条件许可,could 为 can 的过去式。 Can you pass me the books? 你能给我递一下书吗 ? Could you help me, please? 请问,你能帮助我吗? What can you
16、 do? 你能干点什么呢? Can you be sure? 你有把握吗? can 和could 只能用于现在式和过去式两种时态,将来时态用 be able to 来表示。 He could help us at all. 他完全可以帮助我们。 With the teachers help,I shall be able to speak English correctly. 由于老师的帮助,我将能准确地讲英语。 may (might) 可以, 表示说话人同意,许可或请求对方许可。 You may take the book home.你可以把书带回家去. May I come in? 我可以
17、进来吗? May I use your dictionary? 我可以用你的词典吗? You may put on more clothes. 你可以多穿点衣服. He said he might lend us some money. 他说他可以借给我们一些钱。 may 否定式为 may not, 缩写形式是 maynt. might 是may 的过去式, 有两种用法, 一种表示过去式，一种表示虚拟语气, 使语气更加委婉, 客气或对可能性的怀疑。 He told me he might be here on time. 他说他能按时间来。 Might I borrow some money
18、now. 我可以借点钱吗? He might be alive.他可能还活着。 must, need, ought to, dare (dared)用法Must 必须,应该,一定,准是, 表示说话人认为有必要做某事, 命令, 要求别人做某事以及对事物的推测。 must 用来指一般现在时和一般将来时, 过去式可用 have to 的过去式代替。 I must finish my work today. 我今天必须完成我的工作。 You mustnt work all the time. 你不能老是工作。 Must I return the book tomorrow? 我必须明天还书吗? Aft
19、er such a long walk, you must be tired. 走了这么长的路,你一定困了。 He must be the man I am looking for. 他一定是我要找的人。 He had to go because of somebodys calling him that day. 那天他要走是因为有人叫他。 must + have + 过去分词,表示现在对过去事物的推测。 He must have told my parents about it. 他一定把这件事情告诉我父母亲了。 He must have received my letter now. 他
20、现在一定收到我的信了。 Its six oclock already, we must have been late again. 已经六点钟了，我们一定又迟到了。 must 和 have to 的区别: must 表示说话人的主观思想, have to 表示客观需要。 You must do it now. 你必需现在就干。(说话人认为必须现在干) I have to go now. 我得走了。(客观条件必须现在走) need 需要 多用在否定式或疑问句中. Need I attend the meeting tomorrow? 我需要明天参加会议吗? You need not hand i
21、n the paper this week. 这一周你不必交论文。 need 是一个情态动词, 他的用法完全和其他情态动词一样, 但 need 还可当作实义动词使用, 这时 need 就象其他动词一样,有第三人称,单复数, 后面加带 to 的动词等特性。 I need a bike to go to school. 我上学需要一辆自行车。 Do you need a dictionary? 你需要词典吗? She needs a necklace. 她需要一条项链。 neednt + have + 过去分词 表示过去做了没必要做的事情。 You neednt have taken it ser
22、iously. 这件事情你不必太认真。 dare 敢 多用在否定或疑问句中。 The little girl dare not speak in public. 小女孩不敢在公众面前说话。 Dare you catch the little cat? 你敢抓小猫吗? dare 除用作情态动词外,更多的是当实义动词使用, 用法同实义动词一样,要考虑人称,单复数,时态等。 Do you dare to walk in the dark? 你敢黑夜走路吗？ He doesnt dare to tell the teacher what happened that day. 他不敢告诉老师那天发生的事
23、。 have to , ought ，will ，Shall , should . ought 应当,应该 后面跟带有 to 的动词不定式。 You ought to read these books if you want to know how to repair the motorcar. 如果你想知道如何修理汽车,你应该读这些书。 You ought to bring the child here. 你应该把孩子带来。 ought + to have done 句型。指过去动作,表示一件事情该做而未做。 You ought to have been here yesterday. 你昨
24、天就应该来。 ought not to have done 句型。表示一件不该做的事情却做了。 You ought not to have taken the book out of the reading-room. 你不应该把书带出阅览室。 will (would)决心,愿望。 would 为 will 的过去式, 可用于各人称。 Ill do my best to catch up with them. 我要尽全力赶上他们。 Ill never do it again, thats the last time. 我再不会做那件事情了,这是最后一次。 He said he would he
25、lp me. 他说他会帮助我。 will, would用于疑问句表示说话人向对方提出请求或询问,用 would 比 will 更婉转,客气。 Its hot. Will you open the windows? 天气太热了,你能打开窗户吗? Will you help me to work it out? 你能帮我解这道题吗? Would you like some coffee？ 给你来点咖啡怎样？ Shall, should表示命令,警告,允诺,征求,劝告,建议惊奇。 You should hand in the exercise book. 你应该交作业本了。 This should
26、be no problem. 这应该没问题。 Shall we go now. 我们现在可以走了吗? Why should I meet him？ 为什么我要见他? have to,不得不,必须,表示客观条件只能如此, 而must 则表示主观思想必须。 I have to go now. 我现在得走了。 I have to cook for my child. 我得给孩子做饭。 You must be here on time next time. 你下次一定要按时来。 We must go to get the timetable ourselves. 我们一定要自己去拿时刻表。练习：1 J
27、ohn_ come to see us tonight, but he isnt very sure yet.A. may B. canC. has to D. must2 They _ do well in the exam.A. can be able to B. be able to C. can able to D. are able to3 -May I take this book out?-No, you_.A. cant B. may not C. neednt D. arent4 You_ go and see a doctor at once because youre g
28、ot a fever.A. can B. must C. dare D. would5 -Can you speak Japanese?-No, I_.A. mustnt B. cant C. neednt D. may not 6-He_ be in the classroom, I think.-No, he _ be in the classroom. I saw him go home a minute ago. A. can; may not B. must; may not C. may; cant D. may; mustnt7-Shall I get one more cake
29、 for you, Dad?-Thanks, but you_, Ive had enough.A. may not B. must not C. cant D. neednt 8 Even the top students in our class cant work out this problem, so it be very difficult.A.may B. must C. can D. need 9 He isnt at school. I think he _ be ill. A. can B. shall C. must D. has to作业：单选1、 His father
30、 _ the Party since 1978 . A joined B has joined C was in D has been in 2、Do you know him well ? Sure .We _ friends since ten years ago . A were B have been C have become D have made 3、How long have you _ here ? About two months. A been B gone C come D arrived 4、Hurry up! The play _ for ten minutes. A
