【正文】 在這種句型中，如介詞前有動詞do，后面應(yīng)接不帶to的不定式；如無do，則接to不定式，即帶do不帶to， 帶to不帶do。 He feels it his duty to help the poor. 如： When our visit to the farm was over, we expected that wewould start back on foot. I decided that I would ask for my money back. 如： ①以下動詞后，只能跟不定式作賓語。 二、作賓語 s no use your pretending that you didn39。如： s no good for you to eat so much fat. s no good eating too much fat. 如： ⒊動詞不定式和動名詞作主語的區(qū)別 s impossible to…結(jié)構(gòu)。 There is no saying what will happen next. simportant for you to keep fit. s dangerous swimming in the sea in windy days. s＋形容詞＋doing s no use sitting here waiting. s no good reading in dim light. s +no good(no use,fun,a pleasure,a waste of time)+doing… 如： Learning without practice is no good. skind of you to help me with my English.=You are kind to helpme with my English. 在不定式前的sb，可看作其邏輯主語。 It seemed impossible to save money. It is stupid of you to write down everything the teachersays. It is difficult for us to finish writing the positionin a quarter of an hour. How long did it take you to finish the work? s our duty to take good care of the old. ①It＋be＋名詞＋to do (2)用it作形式主語，把真正的主語不定式置于句后，常用于下列句式中。如： 動詞不定式作主語時，句子的謂語動詞常用單數(shù)，其位置有以下兩種： 如果在省略的不定式結(jié)構(gòu)中含有be，have，have been，這些詞要保留。例如： I’m sorry to have kept you waiting. 3．不定式的語態(tài) 當(dāng)不定式邏輯上的主語是這個不定式所表示的動作的承受者時，不定式一般要用被動形式。例如： I saw him go out. 2）如果謂語表示的動作（情況）發(fā)生時，不定式表示的動作正在進(jìn)行，這時不定式就要用進(jìn)行式。） There is nothing to be done. （某東西壞了，無法使之恢復(fù)正常。如： He is hard to talk to. （to talk to him） The book is difficult to understand. （to understand the book） ④在there be結(jié)構(gòu)中，當(dāng)說話人考慮的是必須有人去完成某件事時，不定式用主動形式；如果說話人強(qiáng)調(diào)的事情本身必須完成，則用被動形式。 I have got a letter to write. （I write letter. ） He needs a room to live in. （He lives in a room. ） I know what to do. （I do what. ） 但這句如改為下列形式，不定式就得用被動形式：I know what is to be done. 這是因為what is to be done是賓語從句，從句中的主語what是動詞do的動作對象。例如： Why not have a rest ? 9）不定式在句中用主動式還是被動式，多數(shù)情況下是容易判斷的，但有時的確比較復(fù)雜，請注意以下幾點： ①不定式修飾的名詞或代詞和不定式邏輯上構(gòu)成主謂關(guān)系時，不定式往往用主動形式。如： To tell the truth, I don’t agree with you. 8）不定式與疑問詞who，which，when，where，how，what等連用，在句中起名詞作用，可充當(dāng)主語、表語、賓語等。例如： The room is big enough to hold us. 6）作表語。如： I am very glad to hear it. The question is difficult to answer. “too + 形容詞或副詞 + 不定式”作狀語。如： I came here to see you. （目的） We were very excited to hear the news. （原因） He hurried to the school to find nobody there. （結(jié)果） To look at him, you would like him. （條件） 目的狀語還可以用in order to或so as to來表示但so as to不能置于句首。如： He had not money and no place to live. ②當(dāng)作定語的不定式所修飾的名詞或代詞是不定式動作的承受者時，不定式既可以用主動語態(tài)，也可用被動語態(tài)，但其含義有所不同。如： I have some books for you to read. ①作定語的不定式如果是不及物動詞，或者不定式所修飾的名詞或代詞是不定式動作的地點、工具等，不定式后面須有相應(yīng)的介詞。另外，在can’t choose but和can’t help but等后面的不定式也省略to。但這些句子如果變成被動結(jié)構(gòu)時，就必須帶to。如：decide，plan，desire，expect，hope, wish，pretend，promise，refuse，afford，agree，ask，fail，tend，pretend，manage 3）作賓語補足語。不定式短語作賓語時，如果還帶有賓語補足語，往往把不定式賓語放在賓語補足語之后，而用it作形式賓語。不定式短語作主語時，往往放在謂語之后，用it作形式賓語。不定式的邏輯主語有時有“for + 名詞或代詞賓格”構(gòu)成。不定式可以帶賓語或狀語構(gòu)成不定式短語，沒有人稱和數(shù)的變化，但有時態(tài)和語態(tài)的變化。 devote…to,face up to（勇敢地面對），look forward to（盼望），object to（反對），take to（養(yǎng) 成習(xí)慣，對……感興趣；開始從事某種活動），be used to（習(xí)慣于）等。 ⒎to在下列短語中是“介詞”，后接動名詞或名詞形式。 It39。 ⒍當(dāng)兩個或更多作用相同的不定式并列使用時，只在第一個不定式前加to。 Why spend such a lot of money? ⒌在why引起的問句中，省略to。 另外，be going to,ought to,used to等也常用于這一結(jié)構(gòu)中。 —OK,I39。 ④—Try to be back by 12,won39。 —I39。 ③—Don39。 —I39。t enough time. ①—Did you go to visit the Great Wall? ⒋在口語中，為避免重復(fù)，常用to代替不定式結(jié)構(gòu)，有時甚至可以把to省略。 The bike needs repairing. ②有些動詞后的動名詞用主動形式，但表示被動意義。 The young man came in without being noticed. ①如果動名詞的邏輯主語為動名詞所表示的動作的承受者，動名詞要用被動語態(tài)，動名詞的被動語態(tài)有一 般式與完成式之分。 We were praised for having finished the work ahead of time. 如： We are not afraid of dying. We are interested in collecting stamps. ①一般式：動名詞的一般式所表示的動作可以是泛指，也可與謂語動詞同時發(fā)生，或發(fā)生在謂語動作之前 、之后。 ⒊動名詞的時態(tài)、語態(tài) 在There be結(jié)構(gòu)中，修飾主語的不定式可用被動，也可用主動。 Can you tell me which is the car to be repaired?（不定式作定語） It was impossible for lost time to be made up.（不定式作主語） s a great honour to be invited to Mary39。如： (2)語態(tài) The teacher happened to be correcting our papers when Icame in. ③進(jìn)行式：表示的動作與謂語動詞同時發(fā)生。m sorry to have kept you waiting. 如： We often hear Dick play the piano in the next room.（play和hear同時發(fā)生） 如： (1)時態(tài) could learn… 以上例句中疑問詞＋不定式部分，均可轉(zhuǎn)換為相應(yīng)的從句形式。 ③I asked Professor Xu how to learn English well. ②Mr. Smith didn39。如： ⒈疑問詞＋不定式結(jié)構(gòu) To tell the truth,the play was a great disappointment tome. ⒊不定式短語還可作獨立成分，用于句首、句中或句末。 ②We have too much to （不定式作定語）。m only too glad to have passed the 。如： m too tired to stay up longer. ④too…to ③only to ②enough…to I39。m not so stupid(a fool) as to put it in 。such…as to 如： We came home after our holiday to find our garden neat and tidy. The room is really fortable to live in. 在部分形容詞后接不定式，用主動形式表示被動意義，這種句型中的主語是不定式的邏輯賓語。 ①We are glad to hear the news. (3)在部分表示感情色彩的形容詞、過去分詞或動詞之后可接不定式，如：astonished,glad,happy,laugh ,pleased, sad,smile,sorry,surprised等。在這種句式中不定式部 分可轉(zhuǎn)換為so that,in order that,成為目的狀語從句，如： Bob took down my telephone number so as(in order)not toforget it. (2)有時為了強(qiáng)調(diào)，不定式前可加in order或so as。 (1) ①I stayed there to see what would happen. 六、不定式作狀語 ①He was not allowed to enter the classroom for being late. 不定式作主語補足語，和主語構(gòu)成一種邏輯上的主謂關(guān)系。 The Party calls on us to increase production and practise economy. (5)部分短語動詞后，常接不定式作賓補，如： I39。如： every day. ②They make the students do too much homework every day. ①I didn39。 (3)感覺動詞和使役動詞后用作賓補的不定式須省略to。 ②I consider him(to be)one of the best biology teachers of No. 1 Middle School. ②I want you to understand the whole passage clearly. 如： ⒈作賓語補足語 如：The man standing at the school gate is Professor Hua. ③All moving bodie