虚拟条件句就是对现实条件的一种虚拟假设，所假设的条件一般不符合事实或与事实相反或在现实中发生的可能性极小。根据时间的不同，虚拟条件句可分为三种，即与现在事实相反的虚拟条件句、与过去事实相反的虚拟条件句及与将来事实相反的虚拟条件句。具体情况请看下表： 条件状语从句 主 句 与过去事实相should /would/could/might + have had + 过去分词 反 + 过去分词 与现在事实相一般过去时(be用would/should/could/might + 动词反 原形 were) 一般过去时或与将来事实相would/should/could/might + 动词should(were to) + 动反 原形 词原形 例句： （1）表示与现在事实相反
If I had enough money now, I would lend it to you.
（2）表示与过去事实相反
If he had taken your advice, he wouldn’t have made such a bad mistake.
（3）表示与将来事实相反
I would go shopping with you if it were to be Sunday tomorrow. 1. 虚拟条件句的倒装
在虚拟条件句中，为了强调所假设条件的虚拟性，或突出说话人的一种主观愿望，虚拟条件句可用倒装结构。虚拟条件句的倒装是通过去掉if，把条件从句谓语中的助动词、情态动词或系动词放在句首实现的。例如：
Had I been（= If I had been ） in that situation， I would not have let the thief escape away with so much money.
Should there be （= If there should be） a drought， what should we do at that time ？
2. 错综时间条件句
有时条件从句的动作和主句的动作发生的时间并不一致，这时谓语动词的形式应根据它所要表示的具体时间来确定。例如：
If we hadn’t been working hard in the past few years ，things wouldn’t be going so smoothly. 3. 含蓄条件句
有时假设的情况并不以条件从句的形式表现出来，而是通过某个介词或介词短语（如：with，otherwise，without，but for，in that position）、上下文或其它方式表现出来。这种句子称为含蓄条件句。例如：
But for the help from you ， I would not have had the chance to go to college. 二、虚拟语气在某些从句中的运用
在某些词或短语后接的从句中要使用虚拟语气，表示愿望、建议或命令等。根据虚拟语气的形式不同，虚拟语气可以分为“should类”和“过去时态类”。
（一）should类
这一类的虚拟语气是通过从句中的谓语动词使用“should +动词原形”体现出来的，should可以省略。其具体运用体现在：
1. 在suggest ， order， demand ， propose， command， request， desire，insist等表示建议、命令、要求、意见的动词后接的宾语从句中要使用虚拟语气。
如：He suggests that she should leave the house at once.
The leader ordered that the task（should） be finished as soon as possible. He proposed that we （should）deal with the problem by the view of development.
2. 与suggest，order，demand，propose，command，request，desire，insist等动词相对应的名词suggestion，order，demand，proposal等后的表语从句或同位语从句中要使用虚拟语气。如：The general sent the order that the battle（should）be held on until the complete failure of the enemy.
My proposal is that we（should） set a deadline for handing in the plan. 3. 在It is/was suggested （ordered，demanded，proposed，etc.）结构以及necessary，essential，important，strange，natural等形容词后的主语从句中要使用虚拟语气。如：
It’s requested that we （should）keep the stability of the society for the people’s peaceful life.
It is necessary that the badly wounded man（should） be treated immediately. （二）过去时态类
英语中，还有一些词或短语后接的从句或句子，也要使用虚拟语气，虚拟语气是通过句中的谓语使用过去的某种时态（如：一般过去时、过去完成时等）来体现的。
1. wish，would rather 后的宾语从句。如：
He wished he had never been involved in such affairs. I would rather you could teach me again. 2. as if，as though引导的从句。如：
The little boy knows so many things as if he was a man. He acted as usual as though nothing had happened.
3. 由if only （要是……，那该多好啊！）引导的惊叹句。如： If only I had passed the test！ If only it stopped raining！
4. It is（about/high） time 后的定语从句。如： It is time we went out for a walk.
It was high time they had begun to prepare the experiment. 三、虚拟语气的其它用法
在英语中，一些表示建议、请求、劝告、愿望、祈祷、祝福或诅咒的句子，也需要使用虚拟语气。如： Would you mind smoking here？ May you be lucky！
Long live the people of China！ God save me.
虚拟语气练习题
1．—The rain is coming down so hard!
—________ my umbrella this morning, I wouldn’t be trapped here now. A．Did I take C．Were I to take 【答案】B 【解析】 【详解】
考查虚拟语气和倒装。句意：——雨下得这么大! ——如果今天早上我拿了伞，我就不会被困在这里了。此句是if引导的虚拟语气，从句与过去的事实相反，用过去完成态。句中将if省略，则把助动词had提到主语前面，故答案为B。
B．Had I taken D．Would I take
2． for the free tickets, I would not have gone to the films so often. A．If it is not C．Had it not been 【答案】C 【解析】 【详解】
考查虚拟语气。句意：如果没有那些免费的票，我不会去影院这么频繁。If虚拟条件句的否定（含蓄条件句）常考两个句型：If it weren’t for…和If it hadn’t been for…，其意为“若不是(有)”“要不是”。从句中如果有助动词had, should或were时，可以省略if，而从句使用倒装语序。故选C。
B．Were it not D．If it were to be
3． ________ for the fact that she broke her leg, she might have passed the exam. A．Hadn’t it been 【答案】B 【解析】 【详解】
试题分析：考查虚拟语气。本题考查与过去事实相反的虚拟语气，故从句用had + v-ed，主句用would/could/should/might + have + v-ed。这里的从句用了倒装结构Had it not been=\" If\" it had not been。句意：要不是她摔断了腿这样的事实，她也许会通过考试。故B正确。 考点：考查虚拟语气
B．Had it not been
C．Was it not
D．Were it not
4． it rain tomorrow, we would have to call off the hike. A．Will 【答案】C 【解析】 【详解】
B．Would
C．Should
D．Were
试题分析：句意：如果明天下雨，我们将取消这次徒步旅行。表示对将来情况的虚拟。从句：①if+主语+were to do ②if+主语+should+do ③if+主语+过去式（be动词用were），主句：主语+should/would+do。当虚拟条件句的谓语动词含有were,should,had时，if可以省略，这时条件从句要用倒装语序，即把were,should,had等词置于句首，选C。 考点：考查虚拟语气
5． They didn’t turn up at the meeting yesterday. Otherwise, they _________ the report. A．had listened to C．should listen to 【答案】D 【解析】 【详解】
试题分析：考查与过去事实相反的虚拟语气。句意：昨天他们没有出现在会议上，否则，他们就听报告了。这里otherwise相当于一个虚拟条件句：if they had turned up at the meeting,,主句应用：would/could/might+have done 结构，所以选D。 考点：考查与过去事实相反的虚拟语气
B．would listen to D．would have listened to
6．Nancy was very disappointed to hear the news. I wish I her about that. A．hadn’t told 【答案】A 【解析】 【详解】
试题分析：考察虚拟语气。动词wish后面的从句使用虚拟语气，如果与现在相反，使用一般过去时；与过去相反，用过去完成时；与将来相反，用过去将来时。句意：听到这个消息，Nancy非常失望。我多么希望我没有告诉她这一点啊！根据句意说明这是与过去的希望相反，过使用过去完成时。故A正确。 考点：考察虚拟语气
点评：动词wish后面的从句要使用虚拟语气。如果与现在事实相反，用过去时；如果与过去事实相反，用过去完成时；如果与将来相反就使用过去将来时。
B．didn’t tell
C．wouldn’t tell
D．can’t tell
7． If John Lennon and Paul McCartney _______ , the pop music of today ________ very different.
A．didn’t meet ; would be B．hadn’t met; would be C．didn’t meet ; would have been D．hadn’t met ; would have been 【答案】B 【解析】 【详解】
试题分析：考查虚拟语气。虚拟语气用于状语从句中，与过去事实相反的假设：If + 主语 + had + 过去分词，主句主语 + should/would/could/might have+过去分词，但是虚拟条件句和主句动作若发生的时间的不一致，主句和从句的谓语要根据各自所指的不同时间选用适当的虚拟语气形式。题文中的主句有表现在时间的today，所以应该是主句主语+should/ would/could/might+动词原形。句意：如果约翰列侬和保罗麦卡特尼没有相遇，那今天的流行音乐将大有不同。故选B。 考点：考查虚拟语气
8．Eliza remembers everything exactly as if it ______ yesterday. A．was happening C．has happened 【答案】D 【解析】 【详解】
考查虚拟语气。句意：伊丽莎记得每件事都很清楚，就好像是昨天发生的一样。as if引导的从句使用虚拟语气。主句中的时态是一般现在时，所以从句用一般过去时来表示对现在事实相反的假设。故选D。
B．happens D．happened
9．You _______ a higher score if you hadn’t repeated the same mistake. My suggestion is that _______and start all over again.
A．should have achieved; you must stay calm C．must have achieved; you should stay calm 【答案】B 【解析】 【详解】
考查虚拟语气。句意：如果你没有重复同样的错误，那么，你本来能得更高的分数。我建议你保持冷静，重新开始。第一句考查对过去的虚拟。条件句用过去完成时态，主句用could/would/might have done 形式。结合句意，第一空应填“could have done”，意为“本可以（能够）做某事”。在第二句中，主语为“the suggestion(建议)”，其后的表语从句中，谓语动词应用（should） do形式的虚拟语气，故第二空填(should) stay calm。综上，B选项切题。
B．could have achieved; you stay calm D．will have achieved; you must stay calm
10．—Did you make it at last?
—Yes. But for your help, it________a serious loss. A．would cause C．would have caused 【答案】C 【解析】 【详解】
B．must have caused D．may cause
考查虚拟语气。答句第二句为含蓄条件句，but for引出虚拟条件，此处表示对过去情况的虚拟，故句子谓语形式为would/should/could/might have done。根据句意可知选C。
11．The newly elected president required at the meeting that the problem ________ be solved before the National Day. A．must C．can 【答案】D 【解析】 【详解】
考查虚拟语气。句意：新当选的总统在会议上要求这个问题在国庆节前必须解决。require表示“要求”之意时，后面跟宾语从句时，要用虚拟语气should +动词原形，should可以省略。故选D。
【名师解析】should+动词原形的虚拟语气。
在表示“坚持”、“命令”、“建议”、“要求”等后的宾语从句要用虚拟语气。这类动词主要有 ：“一个坚持(insist)、两个命令(order, command)、三个建议(advise, suggest, propose)、四个要求(demand, require, request, ask)”这类虚拟语气由“should+动词原形”构成，其中的should通常可以省略。如
He insisted that I (should) go with them. 他坚持要我同他们一起去。 He ordered that it (should) be sent back. 他命令把它送回去。
The doctor advised [suggested] that he (should) not smoke. 医生建议他不要抽烟。 He requires that I (should) appear. 他要求我出场。
注：这类句子有时可用于被动结构，前面用先行词it作主语，代指后面的从句。如： It was proposed that this matter be discussed next time. 有人提议这事下次再讨论。 动词insist后接宾语从句时除可用虚拟语气外，也可用陈述语气。两者的区别是若是谓语动词所表示的动作尚未发生或尚未成为事实，则用虚拟语气；若谓语动词所表示的动作已经发生或已经成为事实，则要用陈述语气。比较： He insisted that I had read his letter. 他坚持说我看过他的信。 He insisted that I should read his letter. 他坚持要我看他的信。
与动词insist相似，动词suggest后接宾语从句时除可用虚拟语气外，也可用陈述语气。两者的区别是，若表示建议时用虚拟语气，此时suggest通常译为“建议”。如果译成“表明，暗示”时，则要用陈述语。比较并体会。
He suggested that we (should) stay for dinner. 他建议我们留下吃饭。 What he said suggested that he was a cheat. 他说的话表明他是个骗子。
B．need D．should
12．If it ________ for her great help then, I would not study English so well now. A．hasn’t been C．hadn’t been 【答案】C
B．wasn’t D．isn’t
【解析】 【详解】
考查虚拟语气。句意：那时候如果没有她的帮助，我英语现在不会学的如此好。根据时间状语then可推断，从句表示与过去事实相反，所以谓语动词用过去完成时。故选C。
13．Lily is a good singer. How I wish I ________ as well as her. A．sing C．had sung 【答案】D 【解析】 【详解】
考查虚拟语气。句意：Lily是一个好歌手。我多么希望我唱得和她一样好啊。wish后的宾语从句使用虚拟语气，根据语境可知，从句表示与现在事实相反，谓语动词应用一般过去时。故选D。
B．will sing D．sang
14．He is not native; if he were, we ______ this discussion over his identity. A．would not be having C．had not had 【答案】A 【解析】 【详解】
试题分析：考查虚拟语气。本题考查的if条件句的虚拟语气，表示与现在的事实相反，if从句中使用过去时(be动词用were),主句中使用“情态动词+动词原形”；句意：他不是本地人。如果他是本地人，我们就不会讨论他的身份了。故A正确。 考点：考查虚拟语气
点评：在条件句的虚拟语气中，如果与现在事实相反，主句中使用“情态动词+动词原形”，从句中使用过去时；如果与过去相反，主句中使用“情态动词+have done”,从句中使用过去完成时。
B．are not having D．will not have
15．Their requirement that he one year's experience is reasonable. A．had C．have 【答案】C 【解析】 【详解】
考查虚拟语气。句意：他们要求他有一年的工作经验是有理由的。Requirement后边用that引导同位语从句，从句中谓语动词用should+动词原形，should可以省略，故选C。
B．has D．would have
16．Ellen is a fantastic dancer. I wish I_________as well as her at last party.
A．dance 【答案】C 【解析】 【详解】
B．will dance C．had danced D．danced
考查虚拟语气。句意：埃伦是个出色的舞者，我多么希望我在上次的舞会上能跳得和她一样好。根据上文wish（动词）可知I______as well as her at last party.做wish 的宾语，是宾语从句。结合宾语从句意思可知句中表达了说话者的一种不大可能实现的愿望，应用虚拟语气；根据句中“at last party（上次舞会）”可知，是对过去情况的虚拟，wish 后的宾语从句对过去的虚拟要使用过去完成时had done。故选C。 【点睛】
wish后跟宾语从句要用虚拟语气，对过去情况的虚拟，谓语动词用过去完成时had done；对现在情况的虚拟，谓语动词用过去式；对将来情况的虚拟，谓语动词用 would/could/might +动词原形。
17．Thank you so much for your kind assistance; otherwise, my son ___________ the project on time.
A．would never have completed C．has never completed 【答案】A 【解析】 【详解】
考查虚拟语气。句意：非常感谢你的帮助；要不然的话，我儿子永远不会按时完成这个项目。根据句意可知“我儿子按时完成了这个项目”，与过去的事实相反，相当于if非真实条件句的主句部分，故A项正确。
B．had never completed D．will never complete
18．If you ______ the Minister of Education, which subject would you rather have _______ from the College Entrance Examination? A．are; included C．were to; include 【答案】D 【解析】 【详解】
考查虚拟语气和动词辨析。句意为：假如你是教育部长，你愿意把哪一科从大学入学考试中删除？第一个空表示对将来的假设，be动词应该用were的虚拟，第二个空remove…from…表示“把……从……中去掉”，故选D。
B．had been; been excluded D．were; removed
19．I’m sorry to say I failed to meet the deadline. With better equipment, I __________ the task on schedule.
A．might have accomplished
B．would accomplish
C．must have accomplished 【答案】A 【解析】 【详解】
D．could accomplish
考查虚拟语气。句意：很遗憾我没有按时完成工作。如果有更好的设备的话，我或许可以如期完成任务的。这是一个含蓄条件句，表示与过去的事实相反的假设，主句用should/could/would/might+have done,故选A。
20．Had he taken his parent’s advice, he ______ having made such a silly mistake now. A．would not regret C．may not regret 【答案】A 【解析】 【详解】
考查混合虚拟语气。句意：如果他听了父母的劝告，他现在就不会后悔犯了这样一个愚蠢的错误了。本句考查if引导的混合条件虚拟语气，即从句和主句根据各自假设的时间不同，分析本句可知，从句与过去事实相反，主句与现在事实相反，故主句中用would/should/could/might do结构。故选A。 【点睛】
虚拟条件句和对应主句的动词形式列表： 与过去事实相反的假设 与现在事实相反的假设 与将来事实相反的假设 条件从句的谓语动词形式 had done 主句谓语动词形式 would/could/might/should have done would/could/might/should do would/could/might/should do B．would not have regretted D．may not have regretted
过去时(was→were) 过去时 (was→were ) ; should do; were to do 通常，在上面表格里反映的是非真实条件句的虚拟语气模式，从句和主句的谓语动词时间是一致的，如果两者时间不一致，此时就是混合型虚拟语气。混合型虚拟语气的使用要求“各自为政”，即从句和主句根据各自假设的时间不同，采用上面表格中对应的的谓语动词形式。
如本句Had he taken his parent’s advice, he would not regret having made such a silly mistake now. 从句是对过去的假设，主句是对现在的假设。故A选项正确。
21．--- Thank you for reminding me of the time, or I late for the flight yesterday.
--- Don’t mention it. A．will have been C．must be 【答案】B 【解析】 【详解】
考查虚拟语气。句意：“谢谢你提醒我时间，否则昨天我要迟到了。”“不客
气。”would+have+done表示对过去事情的假设，意思是“本来会做”。故B选项正确。
B．would have been D．could be
22．______ for the fire at Notre Dame de Paris, a church famous for its large collection of art treasures, I would be there for a visit this summer vacation. A．Had it not been C．Were it not be 【答案】A 【解析】 【详解】
考查省略if的虚拟语气。句意：如果不是巴黎圣母院的大火，这个以收藏大量艺术珍品而闻名的教堂，我今年暑假就会去那里参观。此处是if引导的虚拟语气，if从句与过去事实相反用过去完成时态，且if省略则把助动词had提到主语的前面去。故选A。 【点睛】
If引导的虚拟语气： 1.表示与现在事实相反的情况
从句：If+主语+动词一般过去时(Be动词用were)主句：主语+
should/would/might/could+do：If I were you，I would take an umbrella.如果我是你，我会带把伞。（事实：我不可能是你） 2.表示与过去事实相反的情况
从句：If+主语+had+done主句：主语+should/would/might/could+have done：If I had got there earlier，I should/would have met her.如果我早到那儿，我就会见到她。（事实：去晚了）
3.表示与将来事实相反
从句：①if+主语+were to do②if+主语+should+do③if+主语+动词一般过去式（be动词用were）主句:主语+should/would/might/could+do:If he should come here tomorrow，I would talk to him.如果他明天来这儿的话，我就跟他谈谈。（事实：来的可能性很小，不可能）
B．Should it not be D．If had it not been
23．The explosion in the chemical plant ______ avoided had the county authorities, aiming too much at short-term interests, performed their duties from the beginning. A．should be 【答案】D 【解析】
B．might be
C．must have been
D．could have been
【详解】
考查虚拟语气。句意：如果县政府从一开始就履行自己的职责而不是过分着眼于短期利益，那么这座化工厂的爆炸本来是可以避免的。分析句子可知，本句是对过去事情的虚拟，if引导的条件句用过去完成时，if省略，句子倒装，所以主句是had the county authorities, aiming too much at short-term interests, performed their duties from the beginning，从句是could have been。故D选项正确。 【点睛】
if虚拟条件句和对应主句的动词形式列表： 与过去事实相反的假设 与现在事实相反的假设 与将来事实相反的假设 条件从句的谓语动词形式 had done 主句谓语动词形式 would/could/might/should have done would/could/might/should do would/could/might/should do 过去时(was→were) 过去时(was→were)；should do； were to do 分析句子可知，本句是对过去事情的虚拟，if引导的条件句用过去完成时，if省略，句子倒装，所以主句是had the county authorities, aiming too much at short-term interests, performed their duties from the beginning，从句是could have been。故D选项正确。
24．If Lincoln had lived, it________ be that his postwar policies would have brought criticism upon him that would________ his reputation. A．might as well … have tarnished C．might as well … tarnish 【答案】B 【解析】 【分析】 【详解】
考查固定搭配。句意：如果林肯还活着的话，他的战后政策也许很可能会给他带来有损他名望的批评。might as well意为“也可以，倒不如”，might well意为“有可能”,根据句意，故排除A、C项错误；根据If Lincoln had lived是虚拟语气，意为“如果林肯还活着”，表示与过去事实相反的虚拟语气，主句使用了would have+过去分词虚拟语气，故B正确。
B．might well … have tarnished D．might well … tarnish
25．In order to succeed, it is compulsory that you ____work with every fiber of your being. A．might 【答案】B
B．should
C．could
D．must
【解析】 【详解】
考查情态动词。句意：为了成功，你竭尽全力地工作是必须的。此处考查It is +形容词+that+主语+should+动词原形(should可以省略)的虚拟语气，故选B项。 【点睛】
本句考查should在虚拟语气中的使用
It is (was)+形容词（或过去分词）+that…结构中，使用某些表示愿望、建议、请求、命令、可能、适当、较好、迫切、紧近、重要等形容词后的主语从句的谓语用虚拟语气，其表达形式为should ＋动词原形或省略should，直接用动词原形。 例如：
It is necessary that we (should) have a walk now.(necessary, should + have) (表示有需要去散步) It is important that every pupil (should) be able to understand the rule of school.(important, should + be) (表示重要的是学生都能了解校规)
It’s important that we (should) take good care of the patient.(important,should + take) (表示重要的是照顾好病人)
It is essential that these application forms be sent back as early as possible.(essential, should be)这些申请表应尽早地寄回,这是很重要的.
26．He would have been willing to accompany me________him how important it was to me. A．if I have told 【答案】B 【解析】 【详解】
考查虚拟语气。句意：如果我告诉他这对我有多重要，他会愿意陪我的。根据主句谓语would have been可知，此处是虚拟语气，这是对过去的虚拟，所以从句谓语用过去完成时（had done），本应该是if I had told him…，然而从句省去if，则要部分倒装，所以是had I told。故选B项。 【点睛】
If条件虚拟语气精要： 1. 与现在事实相反
If +主语+ did/were(从句)，主语+would/should/could/might + do(主句) 2. 与过去事实相反
If +主语+ had done(从句)，主语+would/should/could/might + have done(主句) 3. 与将来事实相反
If +主语+ did/were to/should + do(从句)，主语+would/should/could/might + do(主句) 4. If条件虚拟句，如省略If，从句要主谓部分倒装。
在本题中，句子与过去事实相反，所以从句应用if I had told him；又因从句省去if，则要部分倒装，故用had I told。
B．had I told
C．should I tell
D．if I could tell
27．---It's a complete pity that you missed the wonderful lecture. ---Terribly sorry! _____my former colleague not come to me unexpectedly. A．Should 【答案】C 【解析】 【详解】
考查虚拟倒装。句意：—你错过了那场精彩的演讲，真是太遗憾了！—非常抱歉，要是我以前的同事没有突然来找我就好了。根据句意可知，此处是对过去的虚拟，从句用过去完成时，谓语动词是had，if可以省略，但是要用倒装语序。故选C。
B．Would
C．Had
D．Did
28．The professor suggested the problem ________ at once. A．referred to be solved C．referred to was solved 【答案】A 【解析】 【详解】
考查过去分词和suggest的用法。句意：教授建议所提到的那个问题应该马上予以解决。the problem 和referred to 之间是被动关系，此处是过去分词做后置定语，相当于定语从句which had been referred to；suugest “建议” 接句子时用虚拟语气（should)+动词原形，其中should可以省略，再根据the problem 和solve之间是被动关系，所以要用被动语态（should ）be solved。故选A。 【点睛】 Suggest用法小结 1.suggest表示建议 1）suggest+doing sth.
He suggested going out for a walk.
2）suggest +(that )+主语+(should) do+sth 其中的should 可以省略
He suggested that you should go there tomorrow.=He suggested you go there tomorrow. 注意,不可以这样说：He suggested you to go there tomorrow.也就是说suggest不可以加不定式的复合结构.
3）it is suggested that +主语+(should )do sth. It is suggested that the work (should) be finished at once.
4）suggestion做主语时,其后的表语从句也用这个结构即：The suggestion is that +主语+should +do sth
His suggestion is that I should leave for Beijing immediately.
2.suggest 表示暗示或表明之意,注意此时做主语时后面的表语从句用陈述语气 Her yawn suggested that she was sleepy.她哈欠连天表明她困了。
B．referred to solving D．referred to must be solved
29．On AIDS Day, the minister of Health Department advised that the problems ________ paid special attention to.
A．referred to being 【答案】B 【解析】 【详解】
B．referred to be C．refer to being D．refer to be
考查非谓语动词和虚拟语气。句意：在艾滋病日，卫生部长建议提到的的这些问题都要被特别关注。分析句子可知，refer to作后置定语修饰the problems ，the problems和refer to是被动关系，要用过去分词形式；因为主句的谓语动词是advise，宾语从句用虚拟语气，符合（should）do sth.的结构，should可以省略，其后the problems和pay attention to是被动关系，be动词用原形。故选B项。
30．—Do you know why the chemical plant wasn’t built here? —Because it ________ too much pollution to the air. A．had caused C．will have caused 【答案】D 【解析】 【详解】
考查虚拟语气。句意：——你知道为什么这里没有化工厂吗? ——因为（如果建了化工厂）它对空气污染太严重。此处省略了从句，表示与现在事实相反，主句用would have+过去分词，故选D。
B．caused
D．would have caused
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