shall would与情态动词can等区别

shall would与情态动词can等区别
前面的如shall可表命令,允许等与后面的情态如何区别.如you shall go.you can go.都是可允许你走的意思

shall两种用法：
1.构成将来时态,单纯表示将来的情况.这是在陈述句中只用于第一人称,在问句中
只用于第二人称.否定式是shan't
2.用在文句中,表示征求对方的意见或指示,用于第一和第三人称.
You shall have the book as soon as i finish it.
我一看完书就把它还给你.
What shall I do now?
现在我该做些什么呢?
shall可以和will作为助动词可以与动词原形一起构成一般将来时.例如：
He will go to Shanghai.
他要去上海.
I shall not come if it rains tomorrow.
如明天下雨我就不来.
shall还可以和will作为助动词可以与动词原形一起构成一般将来时,例如：
I shall study harder at English.我将更加努力地学习英语.
He will go to Shanghai.他要去上海.
would的用法：
(will 的过去式)
1.表示过去将来时,用于第二、三人称](第一人称英国用 should,美国用 would)
将,会
He said he would come.
他说他要来.
2.表示意愿“愿; 偏要,肯”
He would eat nothing.
他不肯吃东西; 他什么也不愿吃.
I told him not to go,but he would not listen.
我叫他别去,可他偏不听 .
He would go in spite of our warnings.
他不听我们的劝告,执意要去.
3.表示过去的习惯动作“常常,总是”
He would sit for hours doing nothing.
过去他常常 坐几个钟头什么事也不做.
He would come to see us on Sundays.
过去星期天他经常来看望我们.
4.表示推测“大概,该是"
I would be about ten when my brother left home.
我哥哥离开家时,我大概十岁左右 .
5.表示某种假设的意志“想要,愿意”
I could do so if I would.
要是我愿意,我能够这样做(但我不愿意).
If you would do this for me,I should be grateful indeed.
若是你愿意为我做这件事,我将万分感激 .
6.表示虚拟,假设,虚 构,用于虚拟条件句的主句第二、第三人称,美国也用于第
一人称“要,会,就会,将要”
They would be killed if the car went over the cliff.
如果汽车翻在悬崖下,他们就会丧命.
They would have been killed if the car had gone over the cliff.
如果汽车当时翻到悬崖下,他们早就丧命了.
7.表示请求或个人想法、看法,使语气更婉转“请”
Would you kindly show me the way to the station?
劳驾,请问到车站的路怎么走?
I would like to speak a few words.
我想讲几句话.
It would seem that he was right.
看来他倒是对的.
8.表示假想的愿望“但愿,要是...多好”
Would [I would] that they were safe home again!
愿他们再能平安回家 !
Would that I were young again.
我若能再年青些该多好啊!
We wish that he would come again.
我们但愿他会再来 .
I would rather you came on Sunday.
.
9.表示能力(=could) “能”
The barrel would hold 100 litres.
这桶能装一百升 .
can的用法：
1.(表示能力、功能)能,会
The classroom can seat thirty students.
这教室能坐三十位学生.
June can drive now.
琼现在会开车了.
2.(表示可能性)可能,可能会
I think the work can be completed ahead of time.
我认为这项工作能提前完成.
3.(表示允许、请求)可以
You can't take the book out of the room.
你不可以将这本书拿出室外.
Can I use your pen?
我可以用一下你的笔吗?
4.(表示命令)必须
If you won't keep quiet you can get out.
你如不保持安静,就请你走.
5.(表示偶然发生的可能性)有时会
It can be quite windy there,especially in spring.
那里有时容易刮风,特别在春季.
6.(表示惊讶)究竟;竟至于
What can it possibly be?
到底那是怎么一回事?