in terms of Should be done用法

Should be done用法  

Should be done用法

sth.should be done 某事应该被做！ sth. should have been done.某事本应该被做，实际没做！
可追问！

should have done的用法

第一句的意思是：
我应该听我父母的话，因为我认为他们说得对。
第二句的意思是：
我当初真应该听我父母的话，因为我认为他们当时说得对。
两句话最大的不同是在于第一句是面向未来，第二句是后悔当初。
should have done表示的意思就是当时应该这么样，（但实际并没有那么做）。

to be done,should be done等等的用法

使用to do来表示被动是因为：用这个不定式结构作宾补.这个不定式表示将要发生的动作.和主语名词有逻辑上动宾关系【很重要】,所以要用主动式表示被动意义.而不用被动的. 如：With a lot of difficult problems to settle , the manager felt worried all the time.【经理解决问题，主语和谓语是一致的，动作由该主语发出。】
而直接使用被动to be done，则它和所修饰的成分有动宾关系，但和句子主语没有动宾关系。对比上文。总的来说，就是主句的主语和该不定式的主语是两个不同的事物，这时候，要只考虑不定式和它的被修饰词之间的关系就可以了。例句：
The weather to be unsteady,this was bound to be a tough journey.(天气变化无常，这注定是趟艰辛的路程。)【to be unstead修饰的是the weather，它却不是整个句子的主语；后面的this(journey)才是主语，和这个不定式没有直接的关系。】
来自QQ'128'278'3799
希望楼主采纳，谢谢昂

should/could/must/might have done用法?

should have done表示本应做而没做
could have done表示本可以做而没做
must have done表示对过去事实的肯定判断，语气较重，即很肯定
might have done=may have done对过去事实的肯定猜测，语气较轻
eg.1.You should have swpet the floor.你本该扫地而没扫。（含责备语气）
2.She could have done better.她本来可以做得更好的。（而实际上做得不够好）含惋惜语气
3.It must have rained yesterday.昨儿个一定下雨了。(看到外面有很明显的下过雨的痕迹时说)
4.He might have had a fever.他可能发烧了吧。（人没来，而谁也不知道原因，就随便猜猜）
should not have done本不该做而做了
could not have done本不可以做而做了
mustn't是禁止 好像没有否定式吧
might not have done对过去事实的否定判断

could have done 和 should have done的用法是否一样？？

could have done ：过去本来能够做到（某事）却没有做。例如
You could have finished your homework yesterday, but you played too much.
should have done：过去本来应该做（某事）却没有做。例如：
You should have been here ten minutes earlier.
祝你开心如意！

英语语法问题could / should have done用法

must have done 对过去的动作的推测。 如; You must have seen him yesterday. 你昨天一定看到他了。
must do 对现在的动作的推测。 如：You must know him well, for you can tell us more about him.
should have done 表示假设， 过去应该做而没有做含有责备的意思。 如; You should have done your home work earlier.
could have done 表示假设， 与过去的事实相反。 如：He could have been very rich, but he cared for no money at all.

should have done 用法中的have可以省略吗？

选B啊！
suggestion表建议的时候后面跟虚拟语气。
没有suggestion后边加should have done的用法！
而且只能省should！
应为：John repeated his suggestion that the meeting (should) be put off.

关于英语情态动词的用法，can/couldn have done与should have done

could have done 本可以做而没有做， 能做而没有做 
shuld have done 1。本应该做而没有做；2。猜测
1. You could have won the first prize if you have spent more time on it. 
2. The ground is wet. It should have rained last night. (猜测)
3. It's 8 o'clcok. I am very hungry. You should have cooked the dinner.(责备)

there should be用法

there should be 是虚拟语气;

would have done 用法

wouldn't have done 表示不会做某事，但是实际上做了。文章中的意思是本来不会降低美国的油气价格。

would have done

是一个固定虚拟语气的用法。

表示对过去事情的假设，意为“本来想做、要做但没做”，使用时大多会给出导致没做成或会这样做的条件。

英汉例句1：

If I had a chance，I would have set off on a journey round the world.
要是有机会，我早就环游世界了。（也可译为对现在的虚拟“要是有机会，我会环游世界”）

英汉例句2：

I would have told you the story about him, but you were not home.

我本来可以告诉你关于他的故事，但是你不在家。（由于：你不在家”这样的条件下，没有告诉关于他的的故事。）

5.would have done与if连用

例句：If I hadn’t been busy that day, I would have gone there with them.

如果那天我不忙，我会和他们一起去那儿。（事实上表示没有由于忙，而没有去。）

在这里也可以不用if

如：I was busy that day. Otherwise I would have gone there with them.

我那天很忙，否则，我就和他们一起去那儿了。

6.文章中lower 在这里作为动词，“降低”的意思。