虚拟语气在各种从句中的用法

虚拟语气在宾语从句中的用法
1、用在动词wish之后
在动词wish后的宾语从句中，从句动词用过去时表示与现在事实相反的愿望；从句动词用过去完成时表示与过去事实相反的愿望；从句中用 “would/could+动词原形”则表示将来难以实现的愿望。
I wish I knew how to operate the machine.我要是会操作这台机器该多好啊。
We wish you had come to our English evening.我们真希望你来参加了我们的英语晚会。
I wish I would try again.我真希望能再试一次。
注意：wish与hope的区别
wish后的宾语从句要用虚拟语气，而hope后的宾语从句要用陈述语气
I hope you'll be better soon.我希望你能很快好起来。
2、用在would rather/would sooner后的宾语从句中
would rather和would sooner可以后接一个有自己的主语的宾语从句，从句内容是宁愿他人做什么或宁愿某物怎么样。这种宾语从句中用过去时表示现在和将来的虚拟内容，用过去完成时表示过去的虚拟内容。
I wish I had seen you yesterday. 我希望昨天能见到你。
I'd rather you went home now.我倒宁愿你现在回家。
I would rather you came tomorrow.我倒宁愿你明天来。
I would rather you had stayed at home last night.我倒宁愿你昨天晚上呆在家里。
3、用在表示命令、建议等意义的动词后的宾语从句中
在表示提议、要求、命令、意愿、决定等意义的动词 (如suggest, decide, require, request, demand, propose, insist, order, prefer等)后的宾语从句中，常用 "should+动词原形"，should常被省略。
-The experiment has failed.实验失败了。
-I suggest you try again. 我建议你再试一次。
Almost all his friends suggested that he visit Mr. Johnson at once.几乎他所有的朋友都建议他去拜访约翰逊先生。
Jane's pale face suggested that she was ill, and her parents suggested that she have a medical examination.詹脸色苍白，表明她病了。她父母建议她做一次体格检查。
I insist that a doctor be sent for immediately.我坚持立即请医生。
巧记10个虚拟动词
1、“一、二、三、四”法。
一个坚持，两个命令，三个建议，四个要求。
一个“坚持(insist)”；两个“命令(order，command)”；三个“建议(suggest, propose, advise)”；四个“要求(demand, require, request, ask)”。
2.“Discrop(无收获)”法。
由这个词的每一个字母联想一个词或两个词:demand，insist，suggest，command, request，require，order，propose。
3.用句联想法。
由句子“I drop cars”的每一个字母联想一个或两个动词:insist，demand，request，order，propose，command，advise，ask ,require，suggest.
六、虚拟语气在主语从句中的用法
1、It +be+形容词+主语从句
“It +is +形容词+that引导的主语从句”句型，用动词原形或“should+动词原形”虚拟语气

。常用于本句型的形容词有:necessary, important, impossible等；还有与表示提议、要求、命令等动词同源的形容词词，如 desirable(←desire), urgent(←urge), advisable(←advise), preferable(←prefer)等。
It is necessary that he listen to the radio frequently.她很有必要常听收音机。
It is strange that he (should) have so many friends. 真奇怪，他居然有这么多的朋友。
2、It+be+过去分词+主语从句
“It +is +过去分词+that引导的主语从句”，可用“（should） +动词原形”。常用于这一句型的过去分词有：suggested, required, requested, demanded, urged, ordered, proposed, desired, advised, etc.
It is ordered that we (should) go at once. 命令我们立刻出发。
It has been decided that the meeting (should) be put off. 已决定推迟会议。
七、虚拟语气在状语从句中的用法
1、虚拟语气在as if/as though引导的方式状语从句中的用法
虚拟语气用在as if/as though引导的方式状语从句中，谓语动词用过去时(be用 were)或"had+ 过去分词" 形式。
When a pencil is partly in a glass of water, it looks as if it were broken.如果把铅笔的部分放在盛水玻璃杯中，铅笔看上去好像断了。
The two strangers talked as if they had been friends for years.那两个陌生人走在一起，好像是多年的朋友。
It seems as if it were spring already.现在仿佛已是春天了。
He spoke as though he had known it.他说起话来，好像他知道了似的。
2、虚拟语气在目的状语从句中的用法
再for fear that, in order that, so that, lest引导的目的状语从句中，谓语动词一般用should(could, might)+动词原形表达虚拟语气，lest引导得从句用should+动词原形,should 可以省略。
I obeyed her lest she should be angry. 我得顺着她，免得她生气。
Be careful lest you fall from that tree.要当心, 以免从树上摔下来。
In order that she could catch the train, she hurried through her work. 为了赶火车，她匆匆做完了她的工作。
I will not make a noise for fear that I might disturb you.我不会做声的，以免打扰你。
八、虚拟语气在表语从句和同位语从句的用法
在proposal, suggestion, order, requirement, desire, decision, advice, plan, necessity等表示提议、要求、命令等名词的后面的表语从句和同位语从句中，可用“动词原形”或“should +动词原形”虚拟语气。
His suggestion is that the meeting be put off. 他的建议是推迟开会。
He made the suggestion that we go by train. 他建议我们坐火车去。
九、It is time that的虚拟形式
在“It is (high) time + that 从句”结构中，用“did 型”虚拟语气，意为“到了做某事的时间了”。意思是早该干而已经有些晚了。
在这种情形下常用过去时。见下表：
句 型
谓 语 动 词 的 虚 拟 形 式
It is(high/about)time that

动词过去式(be多用were)
It is high time that you caught the bus.是你该赶车的时候了。
It is (high) time that you went to school.到了你上学的时间了。
十、比较if only与only if
only if表示“只有”；“if only”则表示"如果……就好了"。If only也可用于陈述语气。
　I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
　If only the alarm clock had rung.当时闹钟响就好了。
If only he comes early.　但愿他早点回来。
If only I had more money! 要是我有更多的钱就好了！
十一、英语中有些惯用语包含着虚拟语气
1、提出请求或邀请
Would you leave a note for her!你要不要给她留张条子。
I should be grateful, if you would be kind enough to help me.如果你愿帮我，我将不胜感激。
2、提出建议或劝告
You might as well put the meeting off for a couple of days.你不妨把会议向后推迟两天。
It would be best if you didn't lend him the money.你不借给他钱那是最好。
3、表示愿望、祝愿或诅咒
Long live…! 万岁……
God bless you! 一路平安。（送别时用语）
Oh，If I knew it is only a trap.啊，我要知道这是陷阱就好了。