Modal Verbs: Permission, Obligation, Prohibition and Necessity
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.
学べること
A complete B2 guide to modal verbs for permission, obligation, prohibition and necessity: must, have to, mustn't, needn't, may, be allowed to, be supposed to, and all their nuanced distinctions.
-
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.
ヒントとコツ (4)
The 'Must' Trap
Context is King
Use 'May' for respect
The 'Needn't Have' Trap
重要な語彙 (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
よくある間違い
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.
このチャプターのルール (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.
クイック練習 (10)
You ___ wear a seatbelt by law.
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To
Which sentence is correct?
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need 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:
I can to go.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed To
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
You ___ smoke in the hospital.
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
We ___ to smoke here.
frontend.learn_grammar.from_rule: Permission: Can, May, Be Allowed To, Be Supposed 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
Find and fix the mistake:
You don't must smoke here.
frontend.learn_grammar.from_rule: Obligation and Necessity: Must, Have To, Need To
Find and fix the mistake:
She mustn't to clean the house.
frontend.learn_grammar.from_rule: Prohibition vs. No Necessity: Mustn't vs. Don't Have To
Score: /10
