【英语语法】一个表格搞定虚拟语气
声明：本文的语法规律为个人的抽象总结，并无任何权威参考。可能有不严谨或错误说法，仅供参考。
虚拟语气简介
虚拟语气(subjunctive mood)在英文中是用来表达假设的场景。例如：“我希望...”、“我建议....”、“如果....”、“...是很重要的”，这些都算是假设的场景。
虚拟语气很简单，一共只有如下三种类型：
- 表示建议：A建议B应该怎么做。例如：“张三建议李四好好学习”。“张三好好学习是非常重要的”
- 表示希望：表示“希望是，但实际不是的事情”。例如：我希望我是一只猫。
- 表示假设：如果....，那我就....（对不会发生的事情做出假设）。例如：如果我中500万，我就做慈善。
对于这三种类型，有固定的句式，记住后多练习就好了。
虚拟语气表格总结
将上节提到的三种虚拟语气类型总结成表格如下：
| 类型 | 句式 | 注意要点 | 例句 |
|---|---|---|---|
| 表示建议 | Sb suggest that sb do sth | ① suggest可以替换为其他词，例如：demand / ask / insist 等。 ② do 只能用原型 |
I suggest that she study more. The teacher insists that he be on time. |
| It's important that sb do sth | ① important可以替换为其他词，例如：essential / necessary 等 ② do 只能用原型 |
It's important that she study more. | |
| 表示希望 | Sb wish (that) sb did / were sth. | ① 表示“希望是，但实际不是的愿望” ② 只能用过去式 ③ be动词的过去式只能用were |
I wish he were here |
| Sb wish (that) sb had done sth. | ① 对“已发生的事”表示希望 | I wish I had studied harder for the exam. 我要是为了考试努力学习就好了（实际上没努力考砸了） |
|
| Sb wish (that) sb/sth would do sth | ① 对“将来不太可能发生或自己无法控制的事”表示希望 | I wish it would stop raining. | |
| 表示假设 | If sb did/were sth, sb would/could/might do sth | ① 对“与事实相反的事”进行假设 ② did/were只能是过去式 ③ be动词的过去式只能用were |
If I were you, I would apologize |
| If sb had done sth, sb would/could/might have done sth | ① 对“与过去事实相反的事进行假设” | If I had studied harder, I would have passed the exam | |
| If sb were to do sth, sb would/could/might do sth | ① 对“与将来可能性极低的事”进行假设 | If I were to win the lottery, I would buy a mansion |
对于非正式的口语来说，不太讲究语法，想用什么用什么。例如：If I was you, I'd apologize.
虚拟语气逐个精讲
表示建议
当在告诉别人应该怎么做时，需要用到“表示建议“的虚拟语气。建议一词是广义的，可以是建议、要求、请求等。
在口语中，一般会使用如下句式：
Sb + suggest / demand/ insist/ ask / ... + (that) sb + should do + sth.
示例：
- I suggest that she should study more.
- The teacher insists that he should be on time.
- The manager demanded that he is on time. （口语中语法比较随意，用不用should都行）
然而，在正式的书面英语中，就要按照严格的语法结构，如下：
Sb + suggest / demand / insist / ask / ... + that sb + do + sth
与口语的区别如下：
- do必须用动词原形。
- 不能使用should
个人认为。在书面用语中，如果使用should显得不太礼貌，因此省略should。但should后要加动词原形却保留了下来。
示例：
- I suggest that she study more. （这里不能用studies）
- The teacher insists that he be on time. （be动词只能用be本身）
对于“表示建议”的虚拟语气，还有一种形容词句式，如下：
It is important / essential / necessary / ... + that sb + do sth.
上述两种相比，只是将“某人建议”改为了“某事很重要”。
口语（非正式）示例：
- It's essential that everyone should be present at the meeting.
- It's necessary that she should study harder to pass the exam.
- It's imperative that the equipment is checked before use.
书面（正式）示例：
- It's essential that everyone be present at the meeting.
- It's necessary that she study harder to pass the exam.
- It's imperative that the equipment be checked before use.
表示希望
当我们幻想一个“不可能发生的事情”、“已经发生了的事情的不同情况”、或“我们无法控制的事情”时，我们就可以用“表示希望”的虚拟语气来表达。
“表示希望”的虚拟语气句式如下：
Sb wish (that) + sb/sth + did / were ...
注意，书面语中，对于be动词，只能用were，不能用was
示例：
- I wish I were taller. (I am not taller)
- She wishes she were in Paris. (She is not in Paris.)
- We wish we knew the answer. (We don't know the answer.)
wish 也可以结合不同的时态使用，但依然只能用过去式，即第一个时态动词必须是过去式。
当希望过去已经发生的事情的不同情况时，使用had done形式。示例：
- We wish he had called earlier. (He didn't call earlier.) 翻译：他要是早点来就好了。
- I wish I had studied harder for the exam. (I didn't study hard.) 翻译：我要是多为这场考试努力学习就好了。
中文通常可以翻译为：要是....就好了。
当希望将来的事情发生时（通常是我们无法控制的或不太可能发生的事情），使用would do形式。示例：
- I wish it would stop raining. (I can't control the weather.)
- We wish the neighbors would turn down their music. (They are playing loud music.)
- They wish the project would be completed on time. (It is not guaranteed to be completed.)
表示假设
当我们假设一件“与现在的事实相反”、“与过去已发生的事实相反”、或“将来可能发生的概率很低的情况”时，就可以用“表示假设”的虚拟语气来表达。
对于不同的时态下，“表示假设”的句式也有稍许不同。
“与现在的事实相反”的句式为：
If + 主语 + were / did + sth, sb would / could / might do + sth
示例：
- If I were the president, I would lower taxes.
- If she were more patient, she could be a greater teacher.
- If it were warmer, we might go to the park.
- If it were not for your support, our lives would be much harder. （要不是你的支持，我们的生活可能会更难）
当假设与过去事实相反时，需要用过去式。句式为：
If + 主语 + had done + sth, 主语 + would / could / should / might + have done + sth
示例：
- If I had studied harder, I would have passed the exam.
- If she had left earlier, she could have caught the train.
- If it had rained, the match might have been canceled.
- If it had not been for her advice, I would have failed. （要不是她的建议，我可能就失败了）
- If it had not been for the rain, we might have arrived on time. (要不是下雨，我们可能就可以准时到达)
当假设将来发生可能性不高的情况时，使用将“were to”表示。句式如下：
If + 主语 + were to do + sth, 主语 + would / could / should / might do + sth.
示例：
- If I were to win the lottery, I would buy a mansion.
- If it were to snow, we might stay indoors.
- If she were to ask for help, I could assist her.
参考资料
- THE SUBJUNCTIVE in 6 simple steps: https://www.youtube.com/watch?v=LXZMKtPpyME
