虚拟语气的一些其他用法
1.在表示愿望、建议、要求、命令等含义的动词及其派生的同根名词后面的主语从句、表语从句及同位语从句中的谓语一般用虚拟语气，即“should +动词原形”或只用动词原形。这类从句常见的动词有：demand, desire, request, require, propose, suggest, recommend, move (提议), order, command, insist等。如：
e.g. It is required that the equipment should be tested again before it is actually put into operation.
这台设备在实际投入运行前要求再测试一次。
e.g. The experts recommended that highways be provided with sensors buried beneath them to emit signals to the car.
专家们建议在公路路面下埋置传感器使之能向汽车发出信号。
e.g. We all insist that we not rest until we finish the work.
大家都坚决要求不完工就不休息。
2.某些形容词后面的主语从句的谓语用虚拟语气
在It is necessary (important, imperative必须的，essential, advisable可取的，better)等句型中的主语从句中，谓语一般用“should +动词原形”或只用动词原形。如：
e.g. It is imperative that Franck do away with his bad habit.
弗兰克改掉他的坏习惯是绝对必要的。
e.g. It is essential that men in space should take their own air with them in order to breathe.
太空人为了呼吸，自备氧气是必不可少的。
3.在wish后的宾语从句中，谓语用虚拟语气。
动词wish后的宾语从句，表示未实现的主观愿望。这时，宾语从句的谓语动词用虚拟语气。如：I wish I could afford a new car. 我要是能买得起一辆崭新的汽车就好了。
具体形式及用法如下表：

宾语从句谓语形式(例词know)

用法

过去式knew

表示现在未实现的愿望

过去完成式had known

表示过去未实现的愿望

过去将来式would know

表示将来不大可能实现的愿望

谓语动词be的过去时为were，适用于一切人称。例如：
e.g. I wish my mother were in good health.我真希望我母亲现在的身体健康。
4.在以as if, as though (好像，似乎)引出的与事实不符的状语从句中，谓语用虚拟语气，其形式一般用动词的过去式表示对现在情况的推测。用过去完成式表示对过去情况的推测。如：
e.g. The moon shines brightly, as if it gave off light by itself.
月亮照得很明亮，仿佛它本身发光一样。
e.g. I was horrified at his appearance. He looked as though he hadn’t slept for weeks.
他的外表吓了我一跳，看上去似乎好几个星期没睡觉。
注：
在由as if, as though引导的从句中通常用虚拟语气，但如果从句中所传述的情况实现的可能性较大，则用陈述语气。如：
e.g. It looks as if it is going to rain.
天似乎要下雨了。
5. 用should (would), could, might + 动词原形的形式表示委婉的虚拟语气
e.g. We’ll have soup to start with. What would you like after that?
我们首先上汤，接着你们喜欢上什么菜?
e.g. The expert explains that the car’s computer might reduce the car’s speed to get it out of danger.
专家解释说汽车上的计算机可以使减速从而避免危险。
6.在“it is (high, about) time+从句”中，表示早该做而没有做的事，含建议的意味，其从句谓语动词用过去式。例如：
Ø It’s (high) time (that) we left now.
现在我们该走了。
It’s (about) time (that) the children went to bed.
孩子们该上床睡觉了。

Ø 课堂练习：
1) We require that the leader ____ us immediately of any change in plans.
A inform B informs C informed D has informed
2) ____ before we depart the day after tomorrow, we should have a wonderful dinner party.
A Had they arrived B Would they arrive C Were they arriving D Were they to arrive
3) ____ for my illness I would have lent him a hand.
A Not being B Had it not been C Without being D Not having been