I: 最基本的虚拟语气句型:
1. 虚拟现在时表示与现在事实相反的假设，其if 从句的谓语形式用动词的过去式(be 一般用were)，主句用would/ should/ could/ might +动词原形。If places were alike, there would be little need for geographers.如果各个地方都一样，就不需要地理学家了。
2. 虚拟过去时是表示与过去事实相反的假设，if 从句的谓语形式用过去完成时即had＋过去分词，主句用would / should / could / might + have +过去分词。If he had known your address yesterday,he would have telephoned you.
3. 虚拟将来时是表示对将来实现的可能性很小的或不确定的假设。If从句的谓语形式用一般过去式或用were to / should +动词原形，主句用would / should/could/ might +动词原形。If he were to leave today, he would get there by Friday
4. 省略if 采用倒装语序的条件句。有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if省去，而将had , should, were 等词提到主语之前，即用倒装结构。If he had worked harder, he would have got through the exams.==>Had he worked harder, he would
have got through the exams.If he were to leave today, he would get there by Friday.==>Were he to leave today, he would get there by Friday.If I were in your place, I wouldn’t do that.==>Were I in your place, I wouldn’t do that.
5. 有时虚拟条件句并没用if 从句表示出来，而是用介词短语(otherwi, or, without, but for)、上下文或其它方式来表示。如：We didn't know his telephone number; otherwi we would have telephoned him. Without you help, I wouldn’t have achieved so much. But for （“要不是时代英语报答案......”prence是什么意思的意思）your help, I would not have succeeded.
II: 虚拟语气在从句中用should的情况:
1. 在表示建议,要求,命令,想法的动词后的从句里, 用should + 动词原形, should 可以省略. 如 advi, agree, command, decide, demand, determine, grant, indicate, insist, order, prefer, propo, request, require, stipulate, suggest, urge, vote.常考到的是: suggest, advi, demand, require, propo, insist, order, request.
His doctor suggested that he (should) take short leave of abnce.
The author propod that TV (should) be turned off at least one hour every day.
2. 在表示建议,要求,命令,想法的名词后的从句里, 用should + 动词原形, should可以省略. 如 advice, decision,agreement, command, decree, demand, determination, indication, insistence, order, preference, proposal, request, requirement, stipulation etc.
It was Bill’s suggestion that everyone (should) have a map.
His suggestion was that everyone (should) have a map.
He gave us a suggestion that everyone (should) have a map.
3. 在It is/was +形容词后的that 腐蚀英文从句中用should的结构, should 可以省略. 这类形容词常见的有: advisable, anxious, compulsory, crucial, desirable, eager, esntial, fitting, imperative(绝对必要), impossible, improper, important, natural, necessary, obligatory, possible, preferable, probable, recommended, urgent, vital etc.
It‘s natural that she (should) do so.
It is esntial that we (should) tell her the news.
4. 在 lest 和sobering for fear that(以免),in ca(以防)从句中用should, should 可以省略.
She walked quietly lest she (should) wake up her roommates.
Have your gun ready in ca we should need it.
III: wish 后的 that 从句中:
1. 表示现在或将来的愿望,从句中过去式.
I wish I knew his address.
I wish I were young.
2. 表示过去没有实现或不可能实现的愿望, 从句用过去完成式或would, could, might + have + 过去分词.
I wish you had written to him.
I wish I could have slept longer this morning, but I had to get up and come to class.
3. 如果将wish改成wished, 其后that 从句中动词的形式不变.
4. 如果that 从句中用would , 一般表示 对现状不满或希望未来有所改变或请求
I wish he would answer my letter.
I wish prices would come down.
I wish you would help me.
I wish you would stop asking silly questions.
IV: 在 It’s about/ high/ first(cond, third etc)time 后的that 从句中,用过去式.表示“该是做什么的时候了”
It is about time you were in bed.
It is high time we left.
It is the first time I came here.
V: 是否英文在would rather, would sooner, would just as soon 后的that从句中,用过去式或过去完成式,表示“宁愿做什么”
I would rather he came tomorrow than today.
John would rather that she had not gone to the party yesterday evening.
VI: 在if only（“如果....就好了”的意思） 感叹句中,谓语动词与wish宾语从句的虚拟形式相同.
If only he didn’t drive so fast!(现在)
专业介绍及就业方向If only she had asked someone’s advice.(过去)
If only the rain would stop.(将来关于爱情的英语句子)
VII: 在as if / as though 从句中,表示和现在事实相反或对现在情况有所怀疑,用过去式;表示过去想象中的动作或情况, 用过去完成式.
He speaks as if he were on the spot.
She spoke to me as if I were deaf.
This device operated as though it had been repaired.
注: 1. 在 as if / as though 句中, 如果有可能成为事实, 用陈述语气林肯公园 变形金刚.
He looks as if he is going to be ill.
2. 在 insist 后的从句中, 冰雪奇缘插曲如果是坚持自己, 用陈述语气, 坚持别人做什么事情, 用虚拟语气.
She insists that she is right.
She insisted that I should finish the work at once.
所谓含蓄虚拟条件句即指将条件从句隐藏在上下文一定的短语中的一类条件句，其主要用法及表现形式可归纳如下：
曼彻斯特大学
1. 将条件隐含在不定式短语中
I would write to her, but I don’t know her address. 我会给她写信的，就是不知道她的地址。(=If I knew her address, I would write to her. But…)
To have studied harder, you would have pasd the examination. 你学习更用功些，你早就考及格了。(=If you had studied harder, you…)
