虚拟语气表示说话人的主观愿望、假设或建议，所表达的动作或状态不是客观存在的事实，而是与事实相反或实现可能性很小。
虚拟语气主要用于：
① 虚拟条件句：If I were you, I would take the job.
② wish / would rather 后的从句：I wish I were taller.
③ 建议、要求、命令类动词后的从句：He suggested that we (should) go early.
④ as if / as though 引导的从句：He acts as if he were the boss.
⑤ It is time... 后的从句：It's time we went home.
⑥ if only 引导的从句：If only I had known earlier!
① "时态往后退一步"——虚拟语气的基本规律是：把本来该用的时态"往后退一步"。
| 事实时态 | 虚拟语气用的时态 |
|---|---|
| 现在时 | 一般过去时（be 用 were） |
| 过去时 | 过去完成时 |
| 将来时 | 过去时 / were to do / should do |
② "结果用 would/could/might/should + 动词"——虚拟条件句的主句部分，用情态动词的过去式 + 动词原形（或完成式）。
虚拟语气 vs 陈述语气：
👉 口诀：虚拟语气 = 时态退一步 + would/could/might/should。
| 与什么时间相反 | if 从句 | 主句 |
|---|---|---|
| 与现在相反 | 一般过去时 （be 用 were） |
would / could / might / should + do |
| 与过去相反 | 过去完成时 (had done) |
would / could / might / should + have done |
| 与将来相反 | 一般过去时 / were to do / should do | would / could / might / should + do |
⭐ 核心提醒：虚拟条件句的 if 从句和主句的时态"配套"出现，不能混用。但与现在、过去、将来相反各有各的搭配。
| 句型 | 从句谓语形式 |
|---|---|
| wish 后 | 与现在相反用过去时；与过去相反用过去完成时；与将来相反用 would/could + do |
| would rather 后 | 与现在/将来相反用过去时；与过去相反用过去完成时 |
| 建议/要求/命令类动词后 | (should) + do |
| as if / as though 后 | 与现在相反用过去时；与过去相反用过去完成时 |
| It is time... 后 | 过去时，或 should + do |
| if only 后 | 与 wish 相同 |
与现在事实相反：
· if 从句：一般过去时（be 用 were）；
· 主句：would / could / might / should + 动词原形。
If I were you, I would take the job.
If he had time, he would help us.
与过去事实相反：
· if 从句：过去完成时（had done）；
· 主句：would / could / might / should + have done。
If I had known the truth, I would have told you.
If he had studied hard, he would have passed the exam.
与将来事实相反：
· if 从句：一般过去时 / were to do / should do；
· 主句：would / could / might / should + 动词原形。
If it rained tomorrow, we would stay at home.
If he were to come tomorrow, I would tell him.
三种时间，三套时态：
| 与什么相反 | if 从句 | 主句 |
|---|---|---|
| 现在 | 过去时（were） | would/could/might/should + do |
| 过去 | had done | would/could/might/should + have done |
| 将来 | 过去时 / were to do / should do | would/could/might/should + do |
记忆要点：
be 动词的特殊形式——在虚拟条件句中，无论主语是什么人称，be 通常用 were。
If I were you, ...（不用 was）
If he were here, ...（不用 was）
👉 口诀：现在过去将来，三种相反三套时态；从句退一步，主句 would。
If I had known the truth, I would tell you.
📌 要点：if 从句和主句的时态必须"配套"，不能一个与现在相反、一个与过去相反。
If I was you, I would take the job.
📌 口诀：虚拟条件句，be 动一律 were。
If he had studied hard, he would pass the exam.
📌 口诀：与过去相反，从句 had done，主句 would have done。
混合虚拟条件句：当 if 从句和主句所指的时间不一致时，从句和主句各自用对应的时态。
If I had taken your advice then, I would be better now.
（从句与过去相反：had taken；主句与现在相反：would be）
If he were a careful person, he wouldn't have made such a mistake.
（从句与现在相反：were；主句与过去相反：wouldn't have made）
省略 if 的倒装：当 if 从句中有 were / had / should 时，可以省略 if，把这三个词提到主语之前，构成倒装。
If I were you, ... → Were I you, ...
If he had known, ... → Had he known, ...
If it should rain, ... → Should it rain, ...
① 混合虚拟条件句——"各按各的时间"：
判断混合虚拟的关键是看从句和主句各自的时间标志：
If you had followed my advice then, you would not be in trouble now.
（then → 从句与过去相反；now → 主句与现在相反）
② 省略 if 的倒装——"were / had / should 提前"：
| 原句 | 倒装句 |
|---|---|
| If I were you, ... | Were I you, ... |
| If he had known, ... | Had he known, ... |
| If it should rain, ... | Should it rain, ... |
注意：只有 were / had / should 这三个词可以提前；如果 if 从句中没有这三个词，就不能省略 if。
👉 口诀：省略 if 看三个词——were, had, should；提前即倒装。
If you had studied hard then, you would pass the exam now.
📌 要点：混合虚拟条件句——各按各自的时间标志走。
Did I know the answer, I would tell you.
📌 口诀：省略 if 只看 were / had / should，其他词不能提前。
wish 后的宾语从句：
· 与现在事实相反：用一般过去时（be 用 were）；
I wish I were taller.
I wish I knew the answer.
· 与过去事实相反：用过去完成时；
I wish I had studied harder.
I wish I hadn't said that.
· 与将来事实相反（表示愿望）：用 would / could + 动词原形。
I wish it would stop raining.
I wish I could fly.
would rather 后的从句：
· 与现在或将来相反：用一般过去时；
I would rather you came tomorrow.
· 与过去相反：用过去完成时。
I would rather you had come yesterday.
| 与什么相反 | wish 从句的时态 | 例句 |
|---|---|---|
| 与现在相反 | 一般过去时（were） | I wish I were you. |
| 与过去相反 | 过去完成时 | I wish I had known earlier. |
| 与将来相反 | would / could + do | I wish it would stop raining. |
wish 与 hope 的区别：
I wish I were a bird.（事实上不是鸟）
I hope he will come tomorrow.（有可能来）
would rather 的两种句型：
I would rather stay at home.（我自己待在家）
I would rather you stayed at home.（宁愿你待在家）
👉 口诀：wish 后时态退一步；would rather 后同样退一步。
I wish I am taller.
📌 口诀：wish 后时态退一步。
I hope I were a bird.
📌 口诀：wish 虚拟，hope 陈述。
I would rather you come tomorrow.
📌 口诀：would rather 自己用原形，别人用虚拟。
在表示建议、要求、命令、坚持等意义的动词、名词、形容词后面的从句中，谓语用 (should) + 动词原形，should 常可省略。
常见动词（一坚持、二命令、三建议、四要求）：
· 一坚持：insist；
· 二命令：order, command；
· 三建议：suggest, advise, propose；
· 四要求：demand, require, request, ask。
此外还有：recommend, urge, desire 等。
常见名词：suggestion, advice, proposal, order, command, demand, requirement, request, recommendation 等。
常见形容词：important, necessary, essential, vital, advisable, desirable 等。
He suggested that we (should) go early.
It is important that he (should) attend the meeting.
The teacher's advice is that we (should) read more books.
① suggest 表示"暗示"时，不用虚拟语气：
He suggested that we (should) start early.（建议，用虚拟）
His expression suggested that he was angry.（暗示，用陈述）
② insist 表示"坚持说"时，不用虚拟语气：
He insisted that we (should) stay for dinner.（坚持要求，用虚拟）
He insisted that he was innocent.（坚持说，用陈述）
如何区分：
③ 常见句型：
| 句型 | 例句 |
|---|---|
| It is + adj. + that + sb. (should) do | It is necessary that he (should) go. |
| It is + done + that + sb. (should) do | It is suggested that we (should) leave. |
| 名词 + is + that + sb. (should) do | His suggestion is that we (should) leave. |
| The + 名词 + is + that + sb. (should) do | The advice is that we (should) leave. |
👉 口诀：一坚持、二命令、三建议、四要求——加 should 可省略。
His expression suggested that he should be angry.
📌 口诀：建议用虚拟，暗示用陈述。
He suggested that we started early.
📌 要点：(should) + 动词原形——动词永远是原形。
as if / as though 引导的从句：
· 与现在事实相反：用一般过去时（be 用 were）；
· 与过去事实相反：用过去完成时；
· 与将来事实相反：用 would / could + 动词原形。
He acts as if he were the boss.
He acted as if he had known the truth.
It is (high) time that... 句型：
· 从句用一般过去时，或 should + 动词原形（should 不能省略）。
It is time we went home.
It is time we should go home.
if only 引导的感叹句：
· 与 wish 类似，表示"要是……就好了"。
If only I knew the answer!
If only I had known earlier!
| 句型 | 从句谓语 | 例句 |
|---|---|---|
| as if / as though | 与现在相反用过去时；与过去相反用过去完成时 | He acts as if he were the boss. |
| It is time that... | 过去时，或 should + do | It is time we went home. |
| if only... | 与 wish 相同 | If only I had known! |
| would rather (that) sb. did | 与现在/将来相反用过去时；与过去相反用过去完成时 | I would rather you came. |
| lest / for fear that / in case | should + do（should 可省略） | He ran fast lest he (should) be late. |
It is time 的两种写法：
if only 与 wish 的对比：
👉 口诀：as if / It is time / if only——都是虚拟语气家族成员。
It is time we go home.
📌 口诀：It is time 后用过去时，或 should + do。
He acts as if he is the boss.
📌 要点：as if 后表示与事实相反时用虚拟语气。
If I had known the truth, I would tell you.
📌 要点：if 从句和主句的时态必须"配套"（除非是混合虚拟条件句）。
If I was you, I would take the job.
📌 口诀：虚拟条件句，be 动一律 were。
If he had studied hard, he would pass the exam.
📌 口诀：与过去相反，从句 had done，主句 would have done。
Did I know the answer, I would tell you.
📌 口诀：省略 if 只看 were / had / should。
I wish I am taller.
📌 口诀：wish 后时态退一步。
I hope I were a bird.
📌 口诀：wish 虚拟，hope 陈述。
I would rather you come tomorrow.
📌 口诀：would rather 自己用原形，别人用虚拟。
His expression suggested that he should be angry.
📌 口诀：建议用虚拟，暗示用陈述；坚持要求用虚拟，坚持说用陈述。
He suggested that we started early.
📌 要点：(should) + 动词原形，永远是原形。
It is time we go home.
📌 口诀：It is time 后用过去时或 should + do。
上海卷对虚拟语气的考查主要集中在：
虚拟语气每年为上海卷直接贡献 2—4 分，是语法填空和中译英的重要语法点。