英語(yǔ)語(yǔ)法歸納與精練根據(jù)以往英語(yǔ)取得高分同學(xué)的經(jīng)驗(yàn)，他們都一致認(rèn)為英語(yǔ)語(yǔ)法和詞匯是學(xué)好、考好英語(yǔ)的重要基礎(chǔ)，其實(shí)完形填空是對(duì)語(yǔ)法、詞匯的綜合考查，但更關(guān)鍵的是學(xué)好此部分有助于對(duì)英語(yǔ)句子結(jié)構(gòu)的分析和理解，有助于學(xué)生掌握靈活多變的句式，這樣不僅有助于學(xué)生做好閱讀理解，而且有助于學(xué)生做好英譯漢，寫(xiě)好作文。因此，我們?cè)诖司帉?xiě)了有關(guān)重點(diǎn)語(yǔ)法的知識(shí)點(diǎn)，并將陸續(xù)登出，同時(shí)將刊登一些試題。希望同學(xué)們認(rèn)真掌握，切不可因不靠它們而忽視了對(duì)英語(yǔ)基礎(chǔ)知識(shí)的掌握。
（一）情態(tài)動(dòng)詞
一、情態(tài)動(dòng)詞的現(xiàn)在完成式的用法情態(tài)動(dòng)詞現(xiàn)在完成式主要有兩個(gè)功能：表示已經(jīng)發(fā)生的情況和表示虛擬語(yǔ)氣。在這兩個(gè)方面must/mustn‘t，；can/cann’t；need/needn‘t；may/mayn’t；might/mightn‘t；should/shouldn’t；ougtht等情態(tài)動(dòng)詞＋完成式表示的意思是有一定區(qū)別的1.表示已經(jīng)發(fā)生的情況。
1）must have+過(guò)去分詞，表示對(duì)已發(fā)生情況的肯定推測(cè)，譯為“（昨天）一定……”。如：My pain apparent the moment I walked into the room， for the first man I met asked sympathetically：“ Are you feeling all right？”
[A] must be [B] had been [C] must have been [D] had to be（答案為C）
2）can‘t / couldn’t have+過(guò)去分詞，表示對(duì)已發(fā)生情況的否定推測(cè)，譯為“（昨天）一定沒(méi)……”。如：Mary my letter； otherwise she would have replied before now. [A] couldn‘t have received [B] ought to have received [C] has received [D] shouldn’t have received（答案為A）
3）may / might have +過(guò)去分詞，表示對(duì)已發(fā)生的事情做不肯定、可能性很小的推測(cè)，或事實(shí)上根本沒(méi)發(fā)生，譯為“也許……”。如：At Florida Power‘s Crystal River plant， a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician. 2.表示虛擬語(yǔ)氣。
1） needn‘t have + 過(guò)去分詞，表示做了不必做的事，相當(dāng)于“didn’t need to do”，譯為“其實(shí)沒(méi)必要……”。如：You needn‘t have come over yourself. As it turned out to be a small house party， we so formally. [A] needn’t dress up [B]did not need have dressed up [C] did not need dress up [D] needn‘t have dressed up（沒(méi)有必要穿的那么正式，體現(xiàn)是說(shuō)話者的建議，實(shí)際結(jié)果是否真的穿的很正式?jīng)]有確定，答案為D）
2）should have +過(guò)去分詞，表示應(yīng)該做某事但實(shí)際上未做，譯為“本應(yīng)該……”should not + have過(guò)去分詞表示本不應(yīng)該做某事但實(shí)際上做了，譯為“本不應(yīng)該……”。如：I regret having left the work unfinished； I should have planned everything ahead carefully.我本來(lái)應(yīng)該事先認(rèn)真地把每件事情規(guī)劃的很好，但實(shí)際上作者還是沒(méi)有規(guī)劃好，以至工作沒(méi)有完成。
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（一）情態(tài)動(dòng)詞
一、情態(tài)動(dòng)詞的現(xiàn)在完成式的用法情態(tài)動(dòng)詞現(xiàn)在完成式主要有兩個(gè)功能：表示已經(jīng)發(fā)生的情況和表示虛擬語(yǔ)氣。在這兩個(gè)方面must/mustn‘t，；can/cann’t；need/needn‘t；may/mayn’t；might/mightn‘t；should/shouldn’t；ougtht等情態(tài)動(dòng)詞＋完成式表示的意思是有一定區(qū)別的1.表示已經(jīng)發(fā)生的情況。
1）must have+過(guò)去分詞，表示對(duì)已發(fā)生情況的肯定推測(cè)，譯為“（昨天）一定……”。如：My pain apparent the moment I walked into the room， for the first man I met asked sympathetically：“ Are you feeling all right？”
[A] must be [B] had been [C] must have been [D] had to be（答案為C）
2）can‘t / couldn’t have+過(guò)去分詞，表示對(duì)已發(fā)生情況的否定推測(cè)，譯為“（昨天）一定沒(méi)……”。如：Mary my letter； otherwise she would have replied before now. [A] couldn‘t have received [B] ought to have received [C] has received [D] shouldn’t have received（答案為A）
3）may / might have +過(guò)去分詞，表示對(duì)已發(fā)生的事情做不肯定、可能性很小的推測(cè)，或事實(shí)上根本沒(méi)發(fā)生，譯為“也許……”。如：At Florida Power‘s Crystal River plant， a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician. 2.表示虛擬語(yǔ)氣。
1） needn‘t have + 過(guò)去分詞，表示做了不必做的事，相當(dāng)于“didn’t need to do”，譯為“其實(shí)沒(méi)必要……”。如：You needn‘t have come over yourself. As it turned out to be a small house party， we so formally. [A] needn’t dress up [B]did not need have dressed up [C] did not need dress up [D] needn‘t have dressed up（沒(méi)有必要穿的那么正式，體現(xiàn)是說(shuō)話者的建議，實(shí)際結(jié)果是否真的穿的很正式?jīng)]有確定，答案為D）
2）should have +過(guò)去分詞，表示應(yīng)該做某事但實(shí)際上未做，譯為“本應(yīng)該……”should not + have過(guò)去分詞表示本不應(yīng)該做某事但實(shí)際上做了，譯為“本不應(yīng)該……”。如：I regret having left the work unfinished； I should have planned everything ahead carefully.我本來(lái)應(yīng)該事先認(rèn)真地把每件事情規(guī)劃的很好，但實(shí)際上作者還是沒(méi)有規(guī)劃好，以至工作沒(méi)有完成。
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