1.The millions of calculations involved, had they been done by hand, ______all practical value by the time they were finished. A. could lose B. would have lost C. might lose D. ought to have lost

　　解析：這個(gè)句子中含有一個(gè)省略if，把助動(dòng)詞提前到主語they之前的虛擬條件句，該條件句表示對(duì)過去情況的假設(shè)，而主句中by the time they were finished 表明主句也應(yīng)該是對(duì)過去發(fā)生的情況的假設(shè)，因而應(yīng)該選(B)would have lost為正確答案。

　　2. Had Paul received six more votes in the last election, he our chairman now.

　　A. must have been B. would have been C. were D. would be

　　解析：這道題目是一個(gè)混合虛擬語氣的句子。條件句省略了if，把助詞had提前到主語前面，表示對(duì)過去情況的假設(shè)，而主句中now表明了對(duì)現(xiàn)在情況的假設(shè)，所以應(yīng)選would(should, could, might)+動(dòng)詞原形這種表達(dá)形式。四個(gè)選項(xiàng)中只有(D)是正確表達(dá)形式，故為正確答案。

　　3. If you Jerry Brown until recently, you’d think the photograph on the right was strange.

　　A. shouldn’t contact B. didn’t contact C. weren’t to contact D. hadn’t contacted

　　解析：until recently，因此(D)是正確答案，而主句是隱含的對(duì)現(xiàn)在情況的假設(shè)，該句是一個(gè)混合虛擬條件句。

　　4. the English examination I would have gone to the concert last Sunday

　　A. In spite of B. But for C. Because of D. As for

　　解析：假設(shè)的情況有時(shí)不是用一個(gè)條件句表示，而是隱含在一個(gè)由介詞如but for、but that、without, 由連詞but、副詞otherwise 、比較級(jí)、形容詞、獨(dú)立主格等表示的上下文中。本句主句表示對(duì)過去情況的假設(shè)，但事實(shí)上由于英語考試而沒有去成，即若不是因?yàn)橛⒄Z考試，我本可以去聽音樂會(huì)，所以應(yīng)選(B)But for為正確答案。

　　5. Look at the terrible situation I am in! If only I your advice

　　A. follow B. would follow C. had followed D. have followed

　　解析：題目中的第一句話表示的是現(xiàn)在真實(shí)的情況，而第二句話中所要表達(dá)的是應(yīng)該做但事實(shí)上沒有做的事，這種情況導(dǎo)致第一句話中真實(shí)情況的發(fā)生，故If only條件句假設(shè)的是過去一種情況，因此應(yīng)該用had +過去分詞，所以正確答案是(C)。

　　6. There is a real possibility that these animals could be frightened, _______a sudden loud noise.

　　A. being there B. should there be C. there was D. there having been

　　解析：句意為：“要是有一聲巨響，這些動(dòng)物會(huì)受到驚嚇，這是有現(xiàn)實(shí)可能性的。”should there be表示虛擬條件句中將來時(shí)間的謂語形式, if省略,所以should與there倒裝。因此B. should there be 就是本題答案 。

　　7、When Edison died, it was proposed that the American people all power in their homes, streets, and factories for several minutes in honour of this great man.

　　A. turn off　B. turned off　C. would turn off　D. had turned off

　　解析： propose是欲望動(dòng)詞,后接的賓語從句或主語從句中謂語要用虛擬語氣：should+動(dòng)詞原形或直接用動(dòng)詞原形。選擇(A). turn off

　　8、I apologize if I you, but I assure you it was unintentional.

　　A. offend　B. had offended C. should have offended　D. might have offended

　　解析：B. had offended 。本題測試交錯(cuò)時(shí)間的虛擬條件句。was 暗示，事情發(fā)生在過去，所以虛擬條件句中的謂語動(dòng)詞應(yīng)該用表示過去時(shí)間的虛擬形式。

　　9、The board deemed it urgent that these files right away.

　　A. had to be printed　B. should have been printed C. must be printed　D. should be printed

　　解析： D. should be printed 。因?yàn)閡rgent是欲望形容詞,在句中作形式賓語it的補(bǔ)足語,所以賓語從句中的謂語需用虛擬語氣:(should)+動(dòng)詞原形(主動(dòng)態(tài)或被動(dòng)態(tài))。

　　10、 The board deemed it urgent that these files right away.

　　A. had to be printed B. should have been printed C. must be printed D. should be printed

　　解析：it是形式賓語，urgent是賓語補(bǔ)足語，that引導(dǎo)的從句是真正的賓語從句，該從句的內(nèi)容被認(rèn)為是urgent(急迫的)，這樣從句的謂語動(dòng)詞要求用虛擬語氣形式，即should(可以省略)+動(dòng)詞原形。因此，本題正確答案是(D)。

　　11、 Jean Wagner’s most enduring contribution to the study of Afro-American poetry is his insistence that it in a religious, as well as worldly, frame of reference.

　　A. is to be analyzed B. has been analyzed C. be analyzed D. should have been analyzed

　　解析：(C)在表示要求、愿望、建議、請(qǐng)求、命令等含義的名詞同位語從句中，從句謂語動(dòng)詞要用虛擬語氣形式，即should(可以省略)+動(dòng)詞原形。

　　12、I would have gone to visit him in the hospital had it been at all possible, but I ____ fully occupied the whole of last week. A. were B. had been C. have been D. was

　　解析：(D)本道題目的前半句話是對(duì)過去情況的一種假設(shè)，但事實(shí)上并沒有發(fā)生，而事實(shí)上沒有發(fā)生的真實(shí)原因是句子的后半部分由but引導(dǎo)的轉(zhuǎn)折句所表述的真實(shí)。因而but所引導(dǎo)的句子中應(yīng)該用表示志過去事實(shí)相符合的表陳述的時(shí)態(tài)，即一般過去時(shí)。

　　13. I apologize if I you, but I assure you it was unintentional.

　　A. offend B. had offended C. should have offended D. might have offended

　　解析：(B)此題要求在if從句中選擇適當(dāng)?shù)膭?dòng)詞形式，以主句中的動(dòng)詞apologize(抱歉)來看，if從句中表達(dá)的內(nèi)容應(yīng)該是過去做的事，因此可以排除(A)，因?yàn)?A)是現(xiàn)在時(shí)。(C)中should+have+過去分詞結(jié)構(gòu)表示本來應(yīng)該做卻沒有做的事，在此不合題意。(D)選項(xiàng)中的might+have+過去分詞表示對(duì)過去發(fā)生的事情很不肯定的猜測，它表達(dá)的內(nèi)容還不能成為事實(shí)，所以藉此道歉真是不知從何說起，因此此處也不合題意。(B)had offended表示當(dāng)時(shí)已經(jīng)發(fā)生了的動(dòng)作。這是復(fù)雜條件句：apologize 是現(xiàn)在，而條件句是表示對(duì)過去假設(shè)的條件句。

　　14. If you hadn’t taken such a long time to get dressed, we’d there by now.

　　A. be B. circles C. is circling D. be circling

　　解析：該句也是一個(gè)復(fù)雜條件句(或稱作混合虛擬條件句)。條件句表示對(duì)過去情況的假設(shè)，而主句表示對(duì)現(xiàn)在情況的假設(shè)，但事實(shí)上卻與此相反，所以正確答案應(yīng)該是(A)。

　　15. The sun rises in the east and sets in the west, so it seems as if the sun ________round the earth.

　　A. were circling B. circles C. is circling D. be circling

　　解析：if引導(dǎo)的從句要求用虛擬語氣，表示同時(shí)或?qū)�來的情況，動(dòng)詞要用過去式(be動(dòng)詞用were)或would(could等)+動(dòng)詞原形，本句話中指的是當(dāng)時(shí)的情況，所以要用過去式，故(A)是正確答案。

　　16. If the Watergate Incident Nixon would not have resigned from the presidency.

　　A. did not occur B. had not occurred C. was not occurring D. be circling

　　解析：(B)had not occurred表示對(duì)過去的虛擬，條件句中要用過去完成式，主句中要用should(would, could, might)+動(dòng)詞原形的過去分詞。

　　17. I hadn’t expected James to apologize but I had hoped .

　　A. him calling me B. that he would call me C. him to call me D. that he call me

　　解析：(B)had hoped是常見的要求其后的賓語從句用虛擬語氣的句型,虛擬語氣would+動(dòng)詞原形。

　　18. George would certainly have attended the proceedings .

　　A. if he didn’t get a flat tire B. if the flat tire hadn’t happened

　　C. had he not had a flat tire D. had the tire not flattened itself

　　解析：表示對(duì)過去情況的假設(shè)，主句動(dòng)詞形式為would(should, could, might)+have+過去分詞，條件句為過去完成式，if可以省略，但要把had提前主語前面。(B)，(D)的表達(dá)不符合英語表達(dá)習(xí)慣，所以(C)是正確答案。

　　19. The teacher suggested that her students experiences with ESP.

　　A. write a composition on their B. to write composition about the

　　C. wrote some compositions of his or her D. had written any compositions for his

　　解析：(A)suggest后面的從句要用虛擬語氣形式，其形式為should(可以省略)+動(dòng)詞原形。

　　20. He speaks Chinese as fluently as if he ______a Chinese.

　　A. were B. had been C. is D. has been

　　解析：(A).表示與現(xiàn)在相反的虛擬。