A．单句填空
1．If I ________(see) it with my own eyes, I wouldn't have believed it.
答案 hadn't seen [句意：如果不是亲眼所见，我是不会相信的。根据主句谓语wouldn't have believed可知，这里考查的是if条件句中对过去情况的虚拟，if条件句中应用过去完成时，故用hadn't seen。]
2．________ (be) there no modern telecommunications, we would have to wait for weeks to get news from around the world.
答案 were [句意：如果没有现代化的电讯，要想收到来自世界各地的消息，我们就不得不等几个星期。本题是if条件句的虚拟语气，表示与现在事实相反。当if省略时，要使用部分倒装。]
3．Ellen is a fantastic dancer. I wish I ________(dance) as well as her.
答案 danced [句意：Ellen是一个极出色的舞者。我希望我能够跳得和她一样好。动词wish后的宾语从句中常用虚拟语气。再根据句意，此处表示对现在情况的一种假设，所以从句中的谓语动词要用一般过去式，故用danced。]
4．They were abroad during the months when we were
carrying out the investigation, or they would ________ (come) to our help.
答案 have come [句意：我们在做调查的那几个月，他们在国外，否则他们会来给我们帮忙的。考查虚拟语气。由句意可知设空处表示与过去事实相反的假设。]
5．If she had been aware that the mushroom were poisonous, she wouldn't ________(pick) them for dinner.
答案 have picked [句意：要是知道这些蘑菇有毒，她不会采来做晚餐了。根据分析可知，if条件句是对过去情况的虚拟，因此主句用wouldn't have picked。]
6．—Who do you think could have done such a foolish thing?
—It ________ (be) Tom, but I'm not sure.
答案 may/might have been [句意：——你认为谁有可能做这样的蠢事？——可能是Tom，但我不确定。根据but I'm not sure可知设空处填may/might have been，表示不确定的可能性。]
7．They would________(arrive) on time for the Winter Olympics, but their car had a flat tyre on the halfway.
答案 have arrived [句意：他们本可以按时参加冬奥会，但他们的轮胎在半路上破了。考查含蓄条件下的虚拟语气，根据but后的句子，可知此处表示与过去事实相反的情况。故用have arrived。]
8．________anyone phone, tell them I'm in conference.
答案 Should [句意：要是有人打电话，就告诉他们我在开会。考查虚拟语气。本句为与将来事实相反的假设，从句用should do, were to do过去式，本句还省略了if, 可还原为If anyone should/were to phone/phoned...。]
9．The examination results suggested that I________in poor health, so the doctor suggested that I________(take) more exercises to improve it.
答案 was; (should) take [句意：检查结果表明我身体不好，所以医生建议我多锻炼来改善身体状况。第一空中的suggest是“暗示，表明”的意思，从句中不用虚拟语气；第二空中的suggest是“建议”的意思，故用should＋v.原形，should可省略。]
10．—You failed to pass the English test again, didn't you?
—Yeah, if only I ________(work) harder at school.
答案 had worked [句意：——你英语测试又没及格，不是吗？——是的，要是我再努力些就好了。考查虚拟语气。根据上文可以判断此处表示过去的情境，if only从句中表过去情况的虚拟语气用过去完成时。]
B．单句改错
1．I would go to my cousin's birthday party last night, but I was not available.
________________________________________________________
答案 go→have gone [句意：要不是昨晚抽不出时间，我就去参加我堂弟的生日聚会了。结合句意和句中的“but I was not available”可知，题干前半句为含蓄条件句；由last night可知，该含蓄条件句表示对过去情况的虚拟，所以谓语形式为would/should/could/might＋have done。]
2．Were he caught the morning train, he would not have been late for the meeting.
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答案 Were→Had [句意：要是他赶上了早晨的火车，那他就不会开会迟到了。本题考查虚拟语气。根据句意，此处是与过去事实相反的假设，条件状语从句应该用过去完成时。本题为省略if的虚拟条件句，应把助动词had提到句首，变为倒装句式。]
3．It was John who broke the window. Why are you talking to me as if I done it?
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答案 在done前加had [句意：是约翰打坏的窗户，你为什么和我说呢？好像是我打坏的一样。本题考查虚拟语气。第一句已经说明是John打坏的窗户，所以第二句中as if后面要用虚拟语气，而且是对过去的虚拟，故用had done。]
4．I should not have laughed if I have thought you were serious.
________________________________________________________
答案 have→had [句意：如果我(当时)认为你是认真的，我就不会笑了。主句中谓语动词使用should not have laughed，表明与过去的事实相反，从句谓语动词应该使用had done形式。]
5．If Mr Dewey been present, he would have offered any possible assistance to the people there.
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答案 been前加had [句意：如果杜威先生在场的话，他肯定会给那里的人们提供任何可能的帮助。结合句意可知，从句表示与过去事实相反的情况，是对过去情况的虚拟和假设，故在been前加had。]
6．Had he predicted the disaster, he wouldn't taken his girlfriend to the 2015 New Year's celebration at the Bund, Shanghai.
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答案 在wouldn't后加have [句意：如果他预料到这场灾难，他就不会带他女朋友去上海外滩参加2015年的新年庆祝活动了。本句中的条件状语从句采用了倒装形式，正常语序为：If he had predicted the disaster, he wouldn't have taken his girlfriend to the 2015 New Year's celebration at the Bund, Shanghai.根据语境可知设空处为与过去事实相反的虚拟语气，故改为wouldn't have taken的形式。]
7．—How I wish I have passed the geography exam!
—So you're sorry that you didn't work hard.
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答案 have→had [句意：——我多么希望通过了地理考试啊！——这么说你对没有努力学习后悔了。考查wish后的宾语从句中虚拟语气的用法。由语境可知此处表示对过去的愿望，故应用过去完成时。]
8．—It will be cool if I won this contest. I don't think I'm good enough, though.
—Give it a shot. You never know.
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答案 will→would [句意：——我要是能赢这场比赛就太好了。但是我想我不够出色。——试试看，很难说。通过句意和won得知，本句为表示将来的虚拟，所以把will改为would。]
9．—Did you make it at last?
—Yes. But for your help, it have caused a serious loss.
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答案 have前加would/could [句意：——最后你成功了吗？——是的，要不是你的帮助，将/可能会有很大的损失。考查虚拟语气。本句为与过去事实相反的假设，所以可用should/would/could/might have done的形式。但should常用于第一人称，might表示的可能性很小。]
10．—Max looks nervous.
—So will you if you had so fierce a competition.
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答案 will→would [句意：——马克斯看上去很紧张。——如果是你参加这么激烈的比赛，你也会紧张的。本句中主句和if条件从句都表示和现在事实相反的假设，可改为：You would also look nervous if you had so fierce a competition.然后考虑采用“so＋be动词/助动词/情态动词＋主语”句型替换主句形式。]
易错题一：几个情态动词的误用
[例1] —Who is the girl standing over there?
—Well, if you ________ know, her name is Mabel.
[错解] will
[错因分析] 考生对must的基本用法掌握不清，而误填其他情态动词。
[答案] must
[心得体会]
[例2] One of our rules is that every student ________ wear school uniform while at school.
[错解] must
[错因分析] 不了解shall的用法的考生此题就填不出来。
[答案] shall
[心得体会]
易错题二：对一些虚拟语气结构的混淆与误用
[例1] —It's a pity that you miss the lecture on nuclear pollution.
—I________ (attend) it, but I was busy preparing for a job interview.
[错解] should attend
[错因分析] 一些考生没有弄明白此处考查含蓄虚拟语气，因而容易误填。
[答案] would/could/should/might have attended
[心得体会]
[例2] Teachers strongly recommend parents ________ (allow) their children under 12 to ride bicycles to school for safety.
[错解] don't allow
[错因分析] 本题考查了虚拟语气在宾语从句中的用法，考生若是对这方面的语法知识掌握得不牢固就很有可能误填。
[答案] not allow
[心得体会]