知识库
先学知识点，再做题检验。当前：情态动词
01. 名词 (8个)
02. 冠词 (5个)
03. 代词 (4个)
04. 形容词与副词 (6个)
05. 介词 (6个)
06. 连词 (4个)
07. 动词时态 (19个)
08. 被动语态 (7个)
09. 情态动词 (4个)
10. 非谓语动词 (8个)
11. 定语从句 (7个)
12. 名词性从句 (8个)
13. 状语从句 (7个)
14. 虚拟语气 (5个)
15. 特殊句式 (8个)
16. 数词 (6个)
17. 直接引语与间接引语 (4个)
18. 句子成分与结构 (7个)
19. 构词法 (4个)
98. 张俊杰英语全语法体系（综合参考） (31个)
99. 英语全语法之简单原则 (12个)
情态动词基础用法
情态动词基础
重点 难度 2/3
核心情态动词
* can/could（能）：I can swim.
* may/might（可以/也许）：May I come in?
* must（必须）：You must finish.
* should（应该）：You should see a doctor.
* will/would（会/愿意）：I will help you.
must vs have to
* must（主观）：I must finish today.
* have to（客观）：I have to wear glasses.
need的两面性
* 情态动词：You needn't go.
* 实义动词：You need to go.
情态动词的时态与替代
难度 2/3
must 的时态替代
* must 没有过去时/将来时
* 过去时用 had to
I had to work late yesterday.
* 将来时用 will have to
I will have to finish it tomorrow.
can 的时态替代
* 现在/一般能力：can
I can swim.
* 过去能力：could / was able to
* 将来能力：will be able to
I will be able to drive after passing the test.
can vs be able to 过去时的区别
* could：表示一般能力/过去经常可以
When I was young, I could run very fast.
* was/were able to：表示过去具体某次成功做到
He was able to swim to the shore after the boat sank.
* 否定式 couldn't 两者通用
used to vs would
* used to do（过去习惯，强调现在已不）
I used to smoke, but I quit.
* would do（过去习惯，不对比现在）
When I was a kid, my mom would read me a story every night.
* used to be（过去是...）：
There used to be a cinema here.(
情态动词表推测
情态动词+完成式用法对比
难度 2/3
情态动词 + have done 核心对比
1.must have done（一定做了——对过去肯定推测）
The ground is wet. It must have rained.
2.can't / couldn't have done（不可能做了——对过去否定推测）
He can't have left, his car is still here.
3.may / might have done（可能做了——对过去不确定推测）
He might have forgotten the meeting.
4.should / ought to have done（本应该做但没做——责备/遗憾）
You should have told me earlier.（但你没说）
5.shouldn't / oughtn't to have done（本不应该做但做了）
You shouldn't have told her the secret.（但你说了）
6.needn't have done（本不必做但做了——做了多余的事）
You needn't have brought food, we have plenty.
7.could have done（本来能做但没做——委婉批评）
You could have helped me.（但你都没帮忙）
情态动词表推测
重点 难度 2/3
对现在推测
* must be（一定）：He must be at home.
* may/might be（可能/也许）
* can't be（不可能）：He can't be 40.
对过去推测
* must have done（一定做了）
* may/might have done（可能做了）
* can't have done（不可能做了）
* should have done（本应该做）
注意
* must表推测只用于肯定句
* can't表推测用于否定（不可能）
* mustn't=禁止（不做推测）