英语虚拟语气的用法

（1）wish + (that) 宾语从句（但愿，希望）
① 表示现在不能实现的愿望： 主语+ wish + (that) + 一般过去时 They wish they were in America. She wishes she could speak English.
② 表示与过去事实相反的愿望：
用以表达说话者某种心愿或者祝愿的句子 叫做祈愿句。 动词原形：God bless you! 愿主保佑你！ May+宾语+动词原形： May you have a good time! May you be happy!
注意 祈使句和其它表示祈愿的句子中必须用动 词原形，不能用其它动词形式。特别要注 意的是，不能把祈使句前的称呼语误认为 主语。 Which of the following is correct? Mary, closes the door. Mary, close the door. Kind to them. Be kind to them.
主语+ wish + (that) + 过去完成时 I wish she had arrived here earlier. She wishes she had not been there then.
③ 表示将来不可能实现的愿望：
注意：


条件从句表示非事实的现在时，其从句要 用一般过去时，但是如果从句谓语动词是 be动词，不管主语为单数还是复数，一 律用were。虽然日常口语中也可以用 was，但是在正式语中（包括各种测试）， 还是该用were。 判断对错： If I was you, I would do the same. If I were you, I would do the same.
②混合虚拟语气
有时主句和条件从句的谓语动词指不同的 时间，这时需要用混合虚拟语气。这种条 件句叫做错综时间条件句。在这种虚拟情 况下，动词形式应根据实际情况灵活使用：
If you hadn’t worked so late last night, you wouldn’t be so sleepy. 如果你昨晚 没有熬夜工作，现在就不会这么困了。 If you had taken the medicine then, you would be much better now. 如果你当时 吃了药，现在就会好多了。
三、虚拟语气
虚拟语气用以表示假定、想象、不可能实 现的愿望等非事实的观念，主要用于条件 状语从句、宾语从句、主语从句、同位语 从句、表语从句、定语从句及其它一些固 定结构中。
1.条件从句中的虚拟语气
当表达非真实的条件，或者对某个既定事 实进行相反的假设和想象时，条件状语从 句就要使用虚拟语气。按照该既定事实发 生的真实时间，条件从句中的虚拟语气可 以分为三种： 非事实的现在（present-unreal）、 非事实的过去（past-unreal）和 非事实的将来（future-unreal）。
通过形容词比较级推断：
A more careful person would not have made so many mistakes. 要是更仔细一 点的人就不会犯这么多错。 =If he/she had been more careful, he/she would not have made so many mistakes.
注意 ① 条件从句和主句中的虚拟语气时间要一致： 如果我知道，我会告诉你。 If I knew, I would have told you. If I knew, I would tell you. 如果你不帮助我们，我们就不会按时完成 它。 If you hadn’t helped us, we would not finish it on time. If you hadn’t helped us, we wouldn’t have finished it on time.
形式
从句： If +主语+ were to do , If +主语+ should + do ， 主句：主语 + would + 动词原形 should + 动词原形（将） could + have done might + have done
If it should rain, we would stay at home. If he should come, I would tell him to wait. If I were to visit Paris, I would let you know.
If you had taken my advice, you wouldn’t have failed. If it had not rained yesterday, the plane would have arrived on time.
（3）非事实的将来（即与将来事实相反
非事实的将来是对将来的某个事实或者状 态进行相反的假设和想象，或者对将来表 示极大的怀疑，其虚拟语气的形式为：if条 件从句的谓语动词用一般过去时，主句谓 语动词则用would + 动词原形。
肯定祈使句
Let+宾语+动词原形 Let me help you with the case. 让我帮 你提箱子。 Let him do it.
否定祈使句
祈使句的否定形式是在肯定祈使句之前加 上否定副词Don’t或Do not，意为“不可”， 但有时也会在句首加never，表示“决不 可”。 Don’t come in. Do not let them touch it. Never tell a lie.
③有的条件从句并不明确表达出来，而是 隐藏在上下文中，或可以通过某些介词短 语、连词、形容词或副词的比较级或不定 式结构等推断出来。
通过上下文推断：
I wouldn’t have done as he did. 我不会 像他那么干。 = I wouldn’t have done as he did if I were he.
条件句的主句谓语动词通常用would+动词 原形，但也可以使用should，could或 might代替would。
（2）非事实的过去（即与过去事实相反）
非事实的过去是对过去已经发生或存在的 某个事实或者状态进行相反的假设和想象。
形式 从句：If+主语+ had done（过去完成式）， 主句： 主语+would + have done Should + have done could + have done might + have done
祈使句语气的加强与缓和
有时，为了加强祈使句的说话语气，可以 在动词原形前加强调词do，即“do+动词 原形”。这时，do要重读。 Do tell her to come. 但是，有时为了缓和说话的语气，则需要 在祈使句之前或句尾加上please。 Come in, please.
祈愿句


通过连词推断：
I would have called you, but I could not find a television. 我本想给你打电话，但 找不到电话。 = I would have called you if I could have found a telephone, b介词短语推断：
(常见的介词有with[要是有], without[要是没有], but for[要不是有], under[在……下]，in[在…… 情况下]等) With the guidance of an expert, they would have succeeded. 如果有专家指导，他们就会成 功了。 =If they had had the guidance of an expert, they would have succeeded. Withou your timely help, I would not have solved the problem so soon. 要不是有你的帮 助，我不会这么快就解决了问题。 =If I hadn’t got your timely help, I would not have solved the problem so soon.
一、陈述语气
陈述语气用以表述一个事实，或否定一个 事实，或对某个事实提起疑问。陈述语气 的这三个含义也分别构成了三种不同的句 型：肯定句、否定句、疑问句。
二、祈使语气

祈使语气通常用以表示命令、禁止、请求、 劝告、建议等主观含义。
祈使句的形式
肯定祈使句 否定祈使句
肯定祈使句
动词原形祈使句 ① 直接用实义动词原形表示，也可用Be+形 容词表示 Open the door. Give me the chair. ② 用Be+形容词或名词表示祈使 Be quick! Be kind to others.
（1）非事实的现在(即与现在事实相反)
从句：If + 主语+ 动词过去式， 主句： 主语+ would + 动词原形（将，愿意） should + 动词原形（将） could + 动词原形（能够） might + 动词原形（或许）
If I had more time, I would study French. (But I don’t have enough time.) If he worked harder, he could learn more quickly. (But he won’t work hard.)