高中英语语法知识点：虚拟语气.docx

1. 掌握虚拟语气的基本用法；
2. 掌握含蓄虚拟条件句的用法；
3. 掌握主从句时间不一致的虚拟条件句的用法；
4. 掌握名词性从句中的虚拟语气的用法；
5. 掌握wish/if only/would rather从句中的虚拟语气的用法。
考向一　if条件句中的虚拟语气

☞If I were you，I would take an umbrella.
如果我是你，我会带把伞。
☞We would have called a taxi yesterday if Harold hadn’t offered us a ride home.
如果昨天哈罗德没送我们回家，我们会打出租车回家的。
【巧学妙记】

考向二　错综时间条件句的虚拟语气 
当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，被称为＂错综时间条件句＂，动词的形式要根据它所表示的时间做出相应的调整。
☞If you had followed the doctor’s advice，you would be better now.
如果你当时听医生建议的话，你现在就好多了。
考向三　省略if的倒装句
在条件句中可省略if，把were，had，should提到句首，变为倒装句式。
☞If I were at school again, I would study harder
→Were I at school again, I would study harder.
如果我重回学校，我会更加努力学习。
☞If you had come earlier, you would catch the bus.
→ Had you come earlier, you would catch the bus.
要是你来的再早点，你可能就赶上公交了。
☞If it should rain tomorrow, we would not go climbing.
→ Should it rain tomorrow, we would not go climbing
要是明天下雨，我们就不去爬山了。
考向四　含蓄条件句中的虚拟语气
有时候，虚拟条件不是通过if引导的条件句来表示，而是暗含在上下文中。
（1）用but for 、without(如果没有）等来代替条件从句。
☞Without electricity human life would be quite different.
=If there were no electricity, human life would be quite different.
如果没有电，人类的生活将会有很大不同。
（2）用otherwise、or(or else)、even though等表示与上文的情况相反，从而引出虚拟语气。
☞I lost your address. Otherwise, I would have visited you long before.
=I lost your address. If I hadn’t lost your address, I would have visited you long before.  
你的地址我弄丢了，要不我早就去拜访你了。
（3）虚拟条件通过but暗示出来。
☞He would have given you more help,but he was too busy. 他本来会给你更多的帮助，但是他太忙了。
也就是说，如果那时他不忙，他可以给你更多的帮助。句中but he was too busy实际上暗示了一个虚拟条件——如果那时他不忙。
☞He would lose weight,but he eats too much. 他本来可以减肥的，但是他吃得太多了。
也就是说，如果他吃得不多的话，他是可以减肥的。句中的but he eats too much实际上暗示了一个虚拟条件——如果他吃得不多。

考向五　名词性从句中的虚拟语气
1．用于表示建议、愿望、命令等动词后的宾语从句中
常见的动词有：demand，order，require，insist，suggest，propose，advise，request，urge，command，prefer，desire，recommend等。宾语从句中的虚拟语气结构为＂should＋动词原形＂，should可以省略。

☞Her mother suggested that she should go and see the doctor.她妈妈建议她去看医生。
【特别提醒】
★ suggest表＂暗示＂，insist表＂坚持认为＂时不用虚拟语气。
试比较：
☞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。
☞He suggested that we (should) stay for dinner. 他建议我们留下吃饭。
☞I suggested that you had a secret understanding with him. 我觉得你与他心照不宣。 
2．用于主语从句中
常见句型：It is important/necessary/urgent/essential/ ... + that...
It is sb’s order/desire/suggestion/advice/ ... + that...
It is suggested/advised/demanded/requested/ ... + that
从句谓语形式：（should+）动词原形
☞It is ordered that the army (should) get there by 4 a.m. 军队必须在上午4点之前到达那里。
☞It is necessary that we (should) clean the room every day. 我们每天打扫房间是有必要的。
☞It is suggested that the meeting (should) be put off till next week.人们建议会议推迟到下周。
3．用于表语从句和同位语从句中
在suggestion，proposal，order，plan，idea，request，advice等名词后的表语从句和同位语从句中要用虚拟语气，其构成是＂should＋动词原形＂，should可以省略。
☞His demand is that the boy should go with him.他要求这个男孩和他一起去。
☞Our suggestion is that you (should) be the first to go. 我们的建议是你应该第一个去。
☞He issued the order that the troops (should) withdraw at once. 他命令部队马上撤退。
考向六　wish 宾语从句中的虚拟语气
1.表示与现在事实相反的愿望，
构成：主语 + wish (that) +从句主语+动词过去式（be一律用were。
☞I wish I knew everything in the world. 我希望我知道世界上的一切。
☞I wish that the experiment were a success. 我希望实验是成功的。
2.表示与过去事实相反的愿望，
构成：主语 + wish (that) + 从句主语 + would/could + have + 过去分词或had + 过去分词。
☞I wish that you had called yesterday. 我希望你昨天打来电话。
☞I didn’t go to the party, but I do wish I had been there. 我没有去参加聚会，但我真希望我去过那儿。
3.表示将来不大可能实现的愿望，
构成：主语 + wish (that) + 从句主语 + would/should/could/might +动词原形。
☞I wish that he could try again. 我希望他能再试一次。
☞I wish that someday I should live on the moon. 我希望有一天我能在月球上生活。
考向七　其他句型中的虚拟语气
1．would rather后的宾语从句中，表示愿望，意为＂宁愿；但愿＂。用一般过去时表示与现在或将来事实相反；用过去完成时表示与过去事实相反。
☞I would rather he had passed the exam.
我宁愿他通过了那次考试。
2．在＂It is (about/high) time＋that从句＂中，谓语动词常用过去式或＂should＋动词原形＂表示虚拟语气，注意should不可省略。
☞It’s high time that we devoted ourselves to environmental protection.
是我们致力于环境保护的时候了。
3．as if，as though引导的表语从句和方式状语从句中常用虚拟语气，与现在事实相反用一般过去时；与过去事实相反用过去完成时。
☞They talked and talked as if they would never meet again.
他们谈啊谈好像永远不会再见面一样。
4．if only引导的感叹句中，用虚拟语气表示愿望。
☞Look at the trouble we’re in.If only we had taken our teacher’s advice！
看看我们所处的困境，要是我们接受老师的建议就好了！