4．If only I________how to operate a computer as you do! A．had known　 　　　　　　　　　　　　　B．would know C．should know 　　　　　　　　　　　　　D．knew 答案　D　[if only引导的句子，与wish用法一样，对现在的情况表示虚拟，用过去时。选D项。句意：要是我像你一样懂得怎样操作计算机就好了。]

5．The chairman requested that________. A．the members studied the problem more carefully B．the problems were more carefully studied C．the problems could be studied with more care D．the members study the problem more carefully 答案　D　[suggest, request，order，demand，insist等表示建议，命令，要求，坚持的词后加宾语从句，要用虚拟语气，动词形式为(should)do。选D项。]

6．I________through that bitter period without your generous help. A．couldn't have gone　 　　　　　　　　　　　　　B．didn't go C．wouldn't go 　　　　　　　　　　　　　　　　　D．hadn't gone 答案　A　[考查虚拟语气的用法。句意：如果没有你的热心帮助，我肯定无法度过那段艰难的日子。根据句意可知，此句为对过去事情的假设，主句应该为“情态动词+ have done”结构，故A项正确。]

7．There was a half smile on his face which suggested that he________happy to have given his life for his country. A．was　　　　　　　　　　　　 　B．should be C．would be 　　　　　　　　　　　D．were 答案　A　[suggest在做“表明，暗示”解释时，后面的从句不用虚拟语气。选A项。句意：他脸上微微的笑容表明他很高兴将自己的生命献给了国家。]

8．If we________the other road, we might have arrived here in time for the meeting. A．take 　　　　　　　　　　　　　B．had taken C．took　　　　　　　　　　　　 　D．have taken 答案　B　[句意：如果我们走另一条路的话，我们或许能够及时到达这里参加这次会议了。根据主句的谓语动词might have arrived可以推出，本句是与过去事实相反的虚拟语气，所以if条件句中应该用过去完成时。]

10．________the present economic crisis go on, the society would face a more troublesome situation.(2013.西安高二检测) A．Would 　　　　　B．Should　 　　　　C．Might　 　　　　D．Could 答案　B　[句意：如果当前的经济危机继续下去，社会将面临更加困难的局面。根据主句中的would可以得知此处是对于将来时间进行的虚拟，从句用if十主语+should do sth，去掉if应把should提前，故选B项。]

11．Why didn't you tell me there was no meeting today? I________all the way here through the heavy snow. A．needn't have driven 　　　　　　　　　B．can't have driven C．mustn't have driven　 　　　　　　　　　D．shouldn't have driven 答案　A　[考查虚拟语气。句意：你为什么不告诉我今天不开会？那样我就不必冒大雪开车来了。这是一种情态动词+have done表示与过去的情况相反的虚拟语气。从语境看应是早知道不开会就没必要冒雪赶路了，因此用needn't。can't“不可能”，mustn't“不许”，shouldn't“不应该”都不符合语境。]

12．You didn't let me drive. If we________in turn, you________so tired. A．drove; didn't B．drove; wouldn't get C．were driving; wouldn't get D．had driven; wouldn't have got 答案　D　[本句是对过去情况的虚拟。句意：如果我们轮流开车的话，你就不会那么累了。对过去虚拟，if条件句用过去完成时，had driven，主句用wouldn't have got。选D项。]

13．Maybe if I________science, and not literature then, I would be able to give you more help.(2011.北京，30) A．studied　 　　　　　　　　　　　　B．would study C．had studied 　　　　　　　　　　　D．was studying 答案　C　[考查虚拟语气。句意：或许要是那时我学的是科学而不是文学，我就能给你更大的帮助。根据从句时间状语then，可知if条件句表示与过去事实相反，要用过去完成时(had done)，故选C项。]

14．John went to the hospital alone. If he________me about it, I would have gone with him.(2010.天津，15) A．should tell 　　　　　　　　　　　　　B．tells C．told 　　　　　　　　　　　　　　　D．had told 答案　D　[考查虚拟语气。句意：约翰独自去了医院。如果他早点告诉我，我就会和他一起去了。根据语境可知是对过去的假设，故从句中用过去完成时。所以选D项。]