【正文】 　　我們認為湯姆是班上最好的學生之一。 　　典型例題　　 Charles Babbage is generally considered　__ the first puter.　 　　A. to invent　B. inventing　C. to have invented　D. having invented　 　　答案：A. 由consider to dosth. 排除B、D。. 此句只說明發(fā)明這一個事實，不定式后用原形即可。而C為現(xiàn)在完成時，發(fā)明為點動詞一般不用完成時，且此處也不強調對現(xiàn)在的影響，因此不選C。 　　3) to be +形容詞　　 Seem,appear,be said,be supposed,be believed,be thought,be known,be reported,hope, wish,desire,want,plan,expect,mean… 　　例句： 　　a.　The book is believed to be uninteresting. 　　人們認為這本書沒什么意思。 　　4)　there be+不定式 　　believe,expect,intend,like,love,mean,prefer,want,wish,undrstand 　　例句： 　　a.　We didn39。t expect there to be so many people there. 　　我們沒料到會有那么多人在哪里。 　　有些動詞需用as 短語做補語，如regard, think believe, take, consider. 　　We regard Tom as our best teacher.　我們認為湯姆是我們最好的老師。 　　Mary took him as her father .　瑪麗把他當作自己的父親。 三、作主語　　easy,difficult,hard,important,possible,impossible,fortable,necessary,better?！?　　the first,the next,the last,the best,too much,too little,not enough,Kind,nice,stupid,rude,clever,foolish,thoughtful,thoughtless,brave,considerate,silly,elfish 　　例句： 　　a.　It39。s easy (for me) to do that. 　　我做這事太容易了 　　b.　It39。s so nice to hear your voice. 　　聽到你的聲音真高興。 　　b.　It39。s necessary for you to lock the car when you do not use it. 　　當你不用車的時候，鎖車是有必要的。 　　c.　It39。s very kind of him to help us. 　　他幫助我們，他真好。 　　d.　It was silly of us to believe him. 　　我們真愚蠢，竟然相信了他。 　　e.　It seemed selfish of him not to give them anything. 　　他不給他們任何東西，這顯得太自私了。 　　注意： 　　1) 其他系動詞如，look，appear等也可用于此句型。 　　2) 不定式作為句子成分時，動詞用單數形式。 　　3) 當不定式作主語的句子中又有一個不定式作表語時，不能用It is… to…的句型 　　(對)To see is to believe.　百聞不如一見。 　　(錯)It is to believe to see. 四、作表語　　不定式可以在句中作表語，起名詞的作用。 　　例如：My work is to clean the room every day. 　　His dream is to be a doctor. 五、作定語　　不定式作表語表示具體動作或將來動作；動名詞作表語表示抽象的一般行為。 　　①To be kind to the enemy is to be cruel to the people. 　?、贛y chief purpose is to point out the difficulties ofthe matter. 　　③What I would suggest is to put off the meeting. 　　當主語和表語都是不定式時，其含義一是條件，一是結果 　?。ɡ伲?。當主語是aim,duty,hope,idea,mista ke,plan,purpose,suggestion等為中心詞的名詞詞組 　?。ɡ冢r，或以what引導的名詞性分句 　?。ɡ郏欢?式說明主語的內容。 　?。ɡ埽㎡ur work is serving the people. 　　（例⑤）What he likes is taking a walk after supper. 　?。ɡ蓿㏕he story told by is interesting. 　?、堍菥鋭用~作表語，與主語部分可以轉換，如Serving thepeople is out work,而⑥句中是現(xiàn)在分詞作表語，說明主語的性質、狀態(tài)，現(xiàn)在分詞具有形容詞的各種特征，另外，動名詞作表語還應與進行時態(tài)區(qū)別開來。 六、作狀語　　1）目的狀語 　　To… only to,in order to,so as to, so (such)… as to…　 　　例句： 　　①He ran so fast as to catch the first bus. 　　他飛快地跑以便趕上第一班車。 　?、贗 e here only to say goodbye to you. 　　我來僅僅是向你告別。 　　2）作結果狀語，表事先沒有預料到的，要放在句子后面。 　?、賅hat have I said to make you angry. 　?、贖e searched the room only to find nothing. 　　3）表原因 　　I39。m glad to see you. 　　典型例題 　　The chair looks rather hard, but in fact it is very fortable to ___. 　　A. sit　B. sit on　C. be seat　D. be sat on 　　答案：，其后應有必要的介詞。當動詞與介詞連用時，常位于形容詞+動詞不定式結構的末尾。 不定式的特殊句型　　so as to 　　1） 表示目的；它的否定式是so as not to do。 　　Tom kept quiet about the accident so as not to lose his job. 　　湯姆對事故保持沉默是為了不丟掉他的工作。 　　Go in quietly so as not to wake the baby. 　　輕點進去，別驚醒了嬰兒。 　　2)　so kind as to 勞駕 　　Would you be so ki