一、insist
1、含义：vt. 坚持;坚决主张，vi. 坚持;强调。
2、用法
insist的基本意思是“坚持”，常用于坚持意见、看法、主张等。insist既可用作及物动词，也可用作不及物动词。作及物动词时,不能用名词、代词或动词不定式作宾语，只能接that引导的从句。
若指尚未发生的动作，从句谓语常用虚拟语气(should+动词原形或直接用动词原形);若表示一个已发生的动作或已存在的状态时，从句谓语多用陈述语气。that有时可以省略。
insist用作不及物动词时，其后常须加介词on〔upon〕,然后接名词、代词或动名词。该动名词前可加物主代词或名词、人称代词的宾格形式作其逻辑主语，该动名词的否定形式是在其前直接加not。
He insisted that he had done right.
他坚决认为自己做对了。
They insist that I stay there for supper.
他们坚决要求让我留下吃晚饭。
二、command
1、含义：n. 命令;指挥;掌握;[计算机] DOS命令 : 引用辅助命令处理器，v. 命令;指挥;掌握;博得。
2、用法
command用作动词是正式用语，表示“命令，要求”时，一般不用作进行时; 其后可接名词或代词作宾语，接带动词不定式的复合结构和that从句时，从句中的谓语动词应用虚拟式，即“(should+)动词原形”。command在书面语体中可以引出直接引语，作“命令道”或“用命令的口气说道”解。
He growled a command to her to stop.
他咆哮着命令她停下来。
The company commander roared his command.
连长高声发布命令。
三、suggest
1、含义：vt. 建议;暗示;使想起;表明;要求。
2、用法
suggest的基本意思是“建议”“提议”，还可表示“暗示，表明”“使想起”等。suggest作“建议”“提议”解后接that从句作宾语时，从句中的谓语动词要用虚拟式; 作“表明，暗示”“使想起”等解时，从句中的谓语动词可用陈述式。
I suggested going for a walk.
我建议去散步。
I suggested to him that we should tackle the problem another way.
我向他建议我们用另一种方式处理这个问题。
四、propose
1、含义：v. 打算;计划;向 ... 提议;求婚;提名。
2、用法
propose的基本意思是“提议，建议”,多指在讨论或争辩中提出明确的意见或建议,强调要求对方予以考虑或同意。引申可表示“打算,计划(做某事)”。可用作及物动词，也可用作不及物动词。用作及物动词时，可接名词、代词、动名词、动词不定式或从句作宾语。后接从句时，从句要用虚拟语气。
I propose an early start tomorrow morning.
我打算明天早上早点出发。
He proposed to buy and run a farm.
他计划购买并经营一个农场。
五、require
1、含义：v. 要求;需要;命令;规定。
2、用法
require接含有被动意义的非谓语动词时，不定式表示被动结构，而动名词表示主动结构; require接that从句时从句中的谓语动词要用虚拟式。
The director required that we should work all night.
主任要求我们通宵工作。
We must not propagate one method and require all localities to adopt it.
我们在宣传上不要只讲一种办法，要求各地都照着去做。
虚拟语气概述：虚拟语气表示说话人所说的话不是事实，而是一种假设、愿望、怀疑或推测。虚拟语气主要用于if条件状语从句，也可用于主语从句、表语从句、宾语从句等。
If I had seen him yesterday, I would have told him the news.
我如果昨天见到他的话，就会把这个消息告诉他的。
It is surprising that you (should) not understand me!
太奇怪了，你竟然不理解我!
1.与现在事实相反的虚拟语气,if从句中的谓语用过去式(be用were),主句用would/could/mightshould+动词原形。
If I had enough money, I would buy myself a computer.
我如果有足够的钱，会为自己买一台电脑。
If I were you, I would forgive Mary.
如果我是你，我就会原谅玛丽。
2.与将来事实相反的虚拟语气，从句谓语过去式(be用were)/should+动词原形/were to+动词原形，主句谓语would/could/might/should do.
If I saw/should see/were to see him tomorrow, I would invite him home.
我如果明天见到他，会邀请他到家里来。
·If I were to do the job, I would do it in a different way.
要是我来做这项工作，我会用另一种方法。
3.与过去事实相反的虚拟语气，主句谓语should/would/could/might+have+过去分词,If 条件从句的谓语形式had+过去分词词。
If we had had enough rain last year,we could have gained a good harvest.
如果去年雨水充足的话，我们可能会有一个好收成。
If the weather had been nice yesterday,we would have gone for a picnic.如果昨天天气好的话，我们就去野餐了。
4. wish后的宾语从句用虚拟语气，从句的谓语形式虚拟情况
与现在事实相反用：过去式(be用were)
与过去事实相反had+过去分词
与将来事实相反would/ could/might+动词原形
I wish (that) I were a bird and could fly freely in the sky.
我希望我是一只鸟，可以在天空中自由地飞翔。
I wish(that)I had met that writer.
我希望遇到过那位作家。
I wish I could help him. 我希望我能帮助他。
5.would rather后的宾语从句用虚拟语气虚拟情况表示现在或将来的愿望，从句的谓语形式过去式( be用were),表示过去的愿望,用had+过去分词
I would rather you came next Saturday.我宁愿你下周六来。
I would rather you had taken the place of me.我宁愿你顶替了我。
6 .as if/as though 引导的虚拟语气
as if/as though引导的虚拟语气谓语的形式与wish后的宾语从句的谓语形式一致。
She talked about the film as if she had really seen it.
她谈论那部影片，就好像她确实看过一样。
It seems as if it were spring already.
现在仿佛已是春天了。
【误区警示】如果与事实相符，as if/as though后的从句用陈述语气。
It looks as if it is going to rain. 仿佛天要下雨。(马上就要下雨)
It seems as if the boy has lost his way,这个男孩好像迷路了。
7.if only...句式用虚拟语气
if only. . 意为“要是······就好了”，其后虚拟语气的用法与wish后的宾语从句的谓语形式一致。
If only I were 20 years younger!
我要是年轻20岁该多好啊!(与现在事实相反)
If only I had come to the party yesterday!
要是昨天我来参加聚会就好了!(与过去事实相反)
If only I could fly to the moon one day.要是有天我能飞上月球就好了。(与将来事实相反)
