Pocket英语语法---四、should的同义词是谁
一、总结
一句话总结：should表示劝告,建议，命令，其同义词是ought to，should强调主观看法，ought to强调客观要求.在疑问句中通常用should代替ought to
1、第23讲 动词的用法？
动词根据功能分为四类：实意动词，系动词，助动词，情态动词
1.动词有数量和时态的变化，时态通常有三大时态：现在，过去和将来时
2.根据动作进行的状态可分为：一般时，进行时和完成时
3.使用动词时通常将1和2结合，例如：一般现在时，过去进行时
动词形态变化有以下几种：动词原形，单三，现在分词，过去式，过去分词。（过去式和过去分词可能不一样)
2、第24讲 情态动词can/could、may/might？
can/could表示能力，用be able to代替can/could 现在/过去的能力，客观可能性，(can的可能性大)，表示请求和允许
may/might表示可能性，may的可能性大，请求,允许,might更委婉，口语中常用回答:Yes,please. No, you can't/mustn't.
3、第25讲 情态动词must/have to？
must/have to表示必须,必要(must表示主观多一些，have to表示客观多一些)，have to有时态和数量的变化.must 和 have to二者的否定意义不大相同.
如:You mustn't go.你不准去.
You don't have to go.你不必去
should表示劝告,建议，命令，其同义词是ought to，should强调主观看法，ought to强调客观要求.在疑问句中通常用should代替ought to
4、第26讲 情态动词need ？
need 需要
a.情态动词
b.实意动词,有第三人称单数和时态的变化，后面可加带to的不定式
情态动词：
He need come here early
He needn't come here early.
实意动词：
He needs to come here early.
He doesn't need to come here early.
Does he need to come here early?
Yes ,he does .No he doesn't.
回答Must 和have to 的提问句时，否定式使用needn't, don't have to,等回答方式。
Must I come here early tomorrow?
No , you needn't /don't have to
5、第27讲.情态动词had.better、Would rather ？
had.better表示最好做某事，had虽然是过去式，但不表征过去,better后面接动词原形
He had better eat more .
You'd better finish it right now.
Would rather 表示 宁愿宁可最好，还是......为好，语感上比had better 要轻
You would rather deal with it now.
否定形式分别为：
Had better not+动词原形，Would rather not+动词原形
He had better not eat any more .
You would rather not deal with it now.
6、第28讲 情态动词used.to,would？
used.to,would表示过去***
1.used to可指过去的状态或情况 ，would则不能
The novel used to be popular.
2.Would表示反复发生的动作，如果某一动作没有反复性就不能用 would ，只能用used to
He would practice English every week.
I used to live in beijing.
3.used to表示过去经常性或***
People used to believe that,the earth was flat.
He would go to the park as soon as he was free.
7、第29讲 情态动词的否定和疑问？
1.情态动词的否定
情态动词+not+动词原形
may not 可能不
can't 不能
2.使用情态动词进行提问
情态动词+主语+动词原形
8、第30讲 情态动词+have+过去分词？
1.情态动词+have+过去分词
a.表达过去事实
b.推测的含义(但助动词should例外)
2.Should +have+过去分词 本应该
Needn't +have+过去分词 本不需要
3.Must have+过去分词 准是已经……can't have+过去分词 不可能已经
9、used to 和would的区别？
分辨would与used to用法
Would与used to都可用来表示过去经常性或习惯性的动作,常常可以换用.如：
(1)When we were boys we used to/would go swimming every summer.
小时候,每到夏天我们都要去游泳.
(2)He used to/would spend every penny he earned on books．
过去,他通常把挣来的钱全花在买书上.
Would与used to都不能用来表示动作发生的具体频度或具体的一段时间.例如,不能说：
(3) I would/used to go to France six times．
(4)He used to live in Africa for twenty years．
上两句应改成：
(5)I went to France six times． 我去过法国6次.
(6)He lived in Africa for twenty years. 他在非洲住过20年.
Would与used to的区别主要有以下几点：
a． Used to可指过去的状态或情况,would则不能.如：
(7)School children used to know the story of how Abraham Lincoln walked five miles to return a penny he"d overcharged a customer．(不能用would)
过去,学校的孩子们都知道亚伯拉罕·林肯怎样步行5英里退还多收顾客1便士的故事.
(8)Yet,he cannot but remember China as it used to be．然而,他不会不记得旧日的中国(不能用would).
b． Would表示反复发生的动作.如果某一动作没有反复性,就不能用 would,只能用 used to.例如：
(9) And from that day on, as soon as the table was cleared and the dishes were gone. Mother would disappear into her sewing room to practice.
从那天起,只要碗盘撤掉、饭桌一清理干净,妈妈就马上躲进做针线活的房间练习起来.(具有反复性)
(10)I used to live in Beijing． 我过去住在北京.(没有反复性)
c． Used to表示过去经常性或习惯性的动作或状态现在已经结束,would则表示有可能再发生.如：
(11)People used to believe that the earth was flat．
过去,人们总以为地球是扁平的.(现在已不再这样认为)
(12)He would go to the park as soon as he was free．
过去,他一有空就去公园.(现在有可能再去)
注意：used to的否定式和疑问句:
(13)过去我不喜欢歌剧.
I used not to like opera．
I usedn"t to like opera．
I didn"t use to like opera．
(14)过去你喜欢歌剧吗?
used you to like opera?
Did you use to like opera?
(15)Didn"t you use to like opera? 你过去不喜欢歌剧吗?
(16)You used to like opera, didn"t you? 你过去喜欢歌剧,是吗?
(17)There used to be a church here, usedn"t there? 过去这里有座教堂,是不是?
二、内容在总结中
来源：https://www.cnblogs.com/Renyi-Fan/p/9644330.html