虚拟语气把动作当作一种只存在于讲话人想象中的“假设”或“推测”，而不是当作客观现实中的真实事件。它表达的是怀疑、忧虑、推测、假设、想象或祝愿等。
I wish I were a white cloud.
但愿我是一片云。
(一)虚拟语气在条件句中的运用
英语中的条件句一共有两种:真实条件句和非真实条件句，虚拟语气用在非真实条件句中。
雅思写作中常用的虚拟条件句可分为以下三类:
1.均现在事实相反的情况;2.与过去事实相反的情况;3.推测将来的情况(也可以理解为与将来事实相反的情况)。 通过下面这个小故事轻松学习虚拟语气。故事人物。
男主人公:郭靖
女主人公:黄蓉
欧阳克
华筝公主
与现在事实相反的情况
当黄蓉扰豫不决要不要嫁给郭靖时，被感动了的华筝愿意成全黄蓉和郭靖，对黄蓉说:
If I were you, I would marry Jing Guo.
如果我是你，我就会嫁给郭靖。(与现在事实相反，华筝是华筝，黄蓉是黄蓉，华筝不可能是黄蓉。)
与过去事实相反的情况
黄蓉和郭靖结婚后过得很幸福，但是有一天闹别扭，愤怒的黄蓉大声对郭靖说:
Are you still missing Hua Zheng?
你是不是还在想着华筝?
No!
没有!
(接下来一句就是与过去事实相反的情况)。
If you had married Hua Zheng 5 years ago, you would have been theemperor's son-in-law.
如果你5年前娶了华筝，你就是金刀验马了。(事实上5年前，郭靖没有娶华筝，他也不是金刀附马。)
推测将来的情况
欧阳克对黄蓉死缠不休，誓娶黄蓉为妻。这时黄蓉为了让欧阳克死心，说了一句与将来事实相反的虚拟语气句。
If you were to be the last man in the world, I would not marry you.
就算你是全世界后一个男人，我也不会嫁给你。(欧阳克当然不可能是世界上后一个男人，这样说只是一个假设，而这种假设是不可能出现的情况。)
与现在事实相反
If I knew the answer to all your questions, I would be a genius.
我如果能回答你所有的问题，我就是天才了。(言下之意:我不能回答你所有的问题，所以我也不是天才。)
If wishes were horses, beggars might ride.
如果幻想能成为马匹，乞丐都有了坐骑。(用现在的话来说就是:如果只是幻想就能得到劳斯莱斯，那么满大街的乞丐都开的是奔驰和宝马。)
与过去事实相反
If we hadn't made adequate preparations, the conference wouldn't have beenso successful.
如果我们不做充分的准备，会议是不会开得这么成功的。
The flood might have caused great damage to the peoplef we hadn't built so many reservoirs.
如果我们没有修建这么多的水库，洪水就会使人们遭受巨大的损失了。
推测将来
If I were to do the work, I should do it in a different way.
要是我做这项工作，我会以不同的方式去做。
If he should have enough money, he would buy it.
要是他有足够钱的话，他会买下它的。
注意:条件句中有“were, had, should, could”时，可以省略“it”，而把“were,had, should, could”放在主语前，用倒装结构。这种用法主要用于书面语中，也是雅思写作的拿分句式!
Were it not for animal experimentation, we wouldn't have made such rapidprogress in medical science.
要是没有动物实验，我们就不会在医疗科技上取得如此快的进展。
Had we known the seriousness of water scarcity, we wouldn't have turned ablind eye to the water pollution.
要是我们早知道淡水短缺的严重性，我们就不会对水污染视而不见了。
Should we act like what we did 5 years ago, we would be penalized severely.
要是我们再像5年前那样做，我们就要受到严惩。
(二)虚拟语气用在suggest, order, demand等后的宾语从句中
在propose, request, desire, insist, require, decide, promise, ask, determine,recommend, advise, intend, beg, resolve，argue, maintain，deserve，urge, instruct,advocate, expect, direct, appoint等意念动词、祈使动词或态度动词后的宾语从句用虚拟语气。这时，谓语动词用动词原形或“should+动词原形”。
They intended that the news (should) be suppressed.
他们打算将这条新闻进行封锁。
He determined that she (should) go at once.
他决定她马上就去。
I prefer that you not eat the meat.
我倾向于你不要吃肉。
(三)虚拟语气用在advice, demand, order等名词后的主语从句、表语从句和同位语从句中常用的这类名词有:advice, demand, order, resolution, decision, proposal, requirement,suggestion, idea, recommendation, preference, request, plan, desire, sentence等。这时，谓语用动词原形或“should+动词原形”。
It is my desire that all the members of the family (should) gather once a year.
我的渴望是所有的家庭成员都能一年聚一次。
》The sentence is that the murderer (should) be shot.
判决的结果是那个谋杀犯被枪决。
The demand is that manu锝擄絻锝掞綁锝愶綌s (should) be written on one side only.
要求是书稿只能写在一面上。
If he is here, he wou一d not let the matter end this way.(误)。
If he were here, he would not let the matter end this way.(正)。
如果他在这儿，他就不会让事情以这种方式结束。
If一had the book，一will lend it to you.(误)。
If I had the book, I should lend it to you.(正)。
如果我有这本书，我就会把它借给你。
If she comes, she would tell you.(误)。
If she comes, she will tell you.(正)。
如果她来，她就会告诉你的。
If he wou一d have come yesterday，一should have told him.(误)。
If he had come yesterday, I should have told him.(正)。
如果他昨天来过了，我就告诉他了。(条件句中不可用would，否则就是语病。
