虚拟语气的一些其他使用方法
1.在表示愿望、建议、需要、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。这种从句容易见到的动词有：demand, desire, request, require, propose1, suggest, recommend, move , order, command, insist等。如：
e.g. It is required that the equipment should be tested again before it is actually put into operation.
这台设施在实质投入运行前需要再测试一次。
e.g. The experts recommended that highways be provided2 with sensors3 buried beneath them to emit4 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.
大伙都坚决需要不完工就不休息。
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 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.
弗兰克改掉他的不好的习惯是绝对必要的。
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，表示未达成的主观愿望。这个时候，宾语从句的谓语动词用虚拟语气。如：I wish I could afford a new car. 我如果能买得起一辆崭新的汽车就好了。
具体形式及使用方法如下表：
宾语从句谓语形式
使用方法
过去式knew
表示目前未达成的愿望
过去完成式had known
表示过去未达成的愿望
过去以后式would know
表示以后不大可能达成的愿望
谓语动词be的过去时为were，适用于所有人称。比如：
e.g. I wish my mother were in good health.我真期望我妈妈目前的身体健康。
4.在以as if, as though 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目前状况的推断。用过去完成式表示对过去状况的推断。如：
e.g. The moon shines brightly, as if it gave off light by itself.
月亮照得非常明亮，仿佛它本身发光一样。
e.g. I was horrified6 at his appearance. He looked as though he hadnt slept for weeks.
他的外表吓了我一跳，看起来好像好几个星期没睡觉。
注：
在由as if, as though引导的从句中一般用虚拟语气，但假如从句中所传述的状况达成的可能性较大，则用陈述语气。如：
e.g. It looks as if it is going to rain.
天好像要下雨了。
5. 用should , could, might + 动词原形的形式表示委婉的虚拟语气
e.g. Well have soup to start with. What would you like after that?
大家第一上汤，接着你们喜欢上什么菜?
e.g. The expert explains that the cars computer might reduce the cars speed to get it out of danger.
专家讲解说汽车上的计算机可以使减速从而防止危险。
6.在it is time+从句中，表示早该做而没做的事，含建议的意味，其从句谓语动词用过去式。比如：
Its time we left now.
目前大家该走了。
Its time the children went to bed.
孩子们该上床睡觉了。
课堂训练：
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 depart7 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
