Chapter in 30 Seconds
Master the nuances of modal verbs to express rules, requirements, and permissions with total confidence.
- Distinguish between internal and external obligations.
- Navigate the subtle differences between prohibition and absence of necessity.
- Express formal and informal permissions using standard and alternative phrases.
你将学到什么
恭喜你进入 B2 阶段！现在的你需要更精准地表达“分寸感”。本章我们将深入探讨情态动词的微妙区别。你将掌握 must（主观义务）与 have to（外部规定）的界限，并彻底分清 mustn't（严禁）和 don't have to（没必要）这两个极易混淆的表达。想象一下，你在跨国公司开会，需要向上级确认 permission（许可），或者在国外旅行时解读当地的规定，准确使用 be allowed to 或 be supposed to 会让你显得更有修养且专业。此外，我们还会攻克 needn't have done 这种“后悔药”式的高级语法，让你能区分“没必要做且没做”和“做了才发现没必要”的微妙心理。学完这 4 条核心规则，你将告别词不达意的尴尬。无论是职场沟通还是日常社交，你都能像地道的母语者一样，游刃有余地表达你的责任、选择和权力。准备好了吗？让我们开始这段精准表达的进阶之旅！
-
Obligation and Necessity: Must, Have To, Need ToMust expresses personal obligation or strong recommendation. Have to expresses external obligation (rules, laws). Need to is neutral necessity. In the past, use had to for all three.
-
Prohibition vs. No Necessity: Mustn't vs. Don't Have ToMustn't = prohibition (it is forbidden — do NOT do it). Don't have to = no obligation (you are free to choose — it is not required). These are opposites in meaning.
-
Permission: Can, May, Be Allowed To, Be Supposed ToCan is the most common way to give or ask for permission. May is more formal. Be allowed to describes permission as a rule. Be supposed to describes expected behaviour.
-
Needn't, Don't Need To, Didn't Need To, Needn't Have: No ObligationNeedn't and don't need to both express no obligation. Needn't have = you did it but it was unnecessary. Didn't need to = it wasn't necessary (and probably you didn't do it).
Learning Objectives
By the end of this chapter, you will be able to:
-
1
By the end you will be able to: Differentiate between internal and external obligation using must and have to.
-
2
By the end you will be able to: Distinguish between prohibition and lack of necessity in professional contexts.
技巧与窍门 (4)
The 'Must' Trap
Context is King
Use 'May' for respect
The 'Needn't Have' Trap
核心词汇 (5)
Real-World Preview
Office Protocol
Review Summary
- Must/Have to + base verb
- Mustn't + base verb
- Be allowed to/May
- Needn't/Don't need to
常见错误
Must is not used in the negative for obligation; use 'don't have to' instead.
Mustn't means it is forbidden, not that it is optional.
Modals do not take the third-person 's' and are followed by the bare infinitive.
本章规则 (4)
Next Steps
You have done an amazing job today! Keep practicing these nuances, and you will sound increasingly natural.
Listen to a news report and note the modal verbs used to describe laws.
快速练习 (10)
I ___ to be at the meeting at 9.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
You ___ finish the work today; tomorrow is fine.
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
Find and fix the mistake:
You don't must smoke here.
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To
You ___ pay for the entry; it's free.
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
___ I ask a question?
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
We ___ to smoke here.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
You ___ pay for this, it's free.
frontend.learn_grammar.from_rule: Needn't, Don't Need To, Didn't Need To, Needn't Have: No Obligation
Find and fix the mistake:
You mustn't go if you are tired.
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
Which sentence is correct?
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To
Find and fix the mistake:
I can to go.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
Score: /10
