Modality A2 B1

Obligation and advice

Express obligation, necessity, lack of necessity, prohibition, advice, expectation, and warning with have to, must, need to, should, ought to, and had better.

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図解ガイド

Obligation and advice: the pressure dial

PRESSURE DIAL
↑ more pressure / less choice

BLOCKED: must not = no permission
  You must not park here.

RULE / NECESSITY: have to / need to / must
  You have to wear a helmet on the site.

WARNING: had better = strong advice + risk

ADVICE / EXPECTED RESULT: should / ought to
  You should take a jacket.
  The package should arrive tomorrow.

NO NEED: don't have to / don't need to
  You don't have to answer every question.

Key negative contrast:
  don't have to = no need
  must not = no permission
↓ less pressure / more choice

Choose the helper by how much pressure there is: no need, good idea, warning, rule, or blocked action.

Introduction

Choice, pressure, and advice

Obligation and advice tell the listener how much choice there is. English does not use one word for every situation. Use have to or must when something is required, and use need to when something is necessary for a result. Use should or ought to for advice, and use had better for urgent advice with a warning feeling. The main action stays in its base form inside these frames: You have to wear a helmet on the site. You should take a jacket.

Core 文法：A2 語彙：A2 Neutral

You have to wear a helmet on the site.

Have to expresses a real requirement, often from a rule or situation.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

have to wear

modal_obligation

Shows a required action with have to + base verb.

ひとまとまりで覚える

a helmet on the site

context

Names what is required and where.

Core 文法：A2 語彙：A1 Neutral

You should take a jacket.

Should gives advice without making it a rule.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

should take

modal_advice

Gives advice with should + base verb.

ひとまとまりで覚える

a jacket

object

Names the recommended thing.

Cognitive metaphor

A pressure dial

Think of these expressions as a pressure dial. Must and have to are high pressure: a rule, duty, or strong demand leaves little choice. Need to is also strong, but the pressure comes from a goal or practical result. Should and ought to are middle pressure: they point to the best, fairest, or expected path. Had better is a warning light: the choice still exists, but ignoring the advice may cause a problem soon.

Core pattern

Core frames

Build the sentence around a fixed frame. Have to and need to change with the subject: I have to, she has to, we need to, he needs to. Must, should, ought to, and had better do not take -s. The main action stays plain: She has to work late tonight. Questions with have to and need to use do: Do we have to pay now? Does he need to bring ID? Questions with should do not use do: Should I call him now? Do not add -s to the main verb: not She has to works.

Core 文法：A2 語彙：A2 Neutral

She has to work late tonight.

Have to changes to has to with she, but the main verb stays in the base form.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

She has to work

subject_obligation

Shows has to for he, she, or it, followed by the base verb work.

ひとまとまりで覚える

late tonight

time

Adds when the obligation happens.

Question 文法：A2 語彙：A1 Neutral

Do we have to pay now?

Questions with have to use do or does.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

Do we have to pay

obligation_question

Forms a question with do + subject + have to + base verb.

ひとまとまりで覚える

now

time

Adds the time of the required action.

Question 文法：A2 語彙：A2 Neutral

Does he need to bring ID?

Need to also uses do or does in questions.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

Does he need to bring

necessity_question

Forms a question with does + subject + need to + base verb.

ひとまとまりで覚える

object

Names what may be necessary.

Question 文法：A2 語彙：A1 Neutral

Should I call him now?

Should does not use do in questions.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

Should I call

advice_question

Asks for advice with should + subject + base verb.

ひとまとまりで覚える

him now

object_time

Completes the action and time.

Contrast

Must, have to, and need to

Must and have to are the closest common confusion. Both can mean obligation, but have to is the normal everyday choice for outside facts, arrangements, and duties: I have to get up at six for work. Must often sounds stronger, more personal, or more official: Visitors must sign in. Need to focuses on necessity for a purpose, not authority: We need to charge the laptop before the meeting. Must I sign both copies? is correct but formal or serious. Do I have to sign both copies? is more common.

Core 文法：A2 語彙：A1 Neutral

I have to get up at six for work.

Have to is the usual choice for daily duties and outside facts.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

have to get up

external_obligation

Shows an everyday obligation caused by a schedule or situation.

ひとまとまりで覚える

at six for work

time_reason

Gives the time and reason for the obligation.

Formal 文法：A2 語彙：A2 Formal

Visitors must sign in.

Must is common in signs, notices, instructions, and official rules.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

must sign in

official_rule

Shows an official rule with must + base verb.

ひとまとまりで覚える

Core 文法：A2 語彙：A2 Neutral

We need to charge the laptop before the meeting.

Need to often focuses on what is necessary for a goal.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

need to charge

practical_necessity

Shows necessity for a practical result.

ひとまとまりで覚える

the laptop

object

Names the thing affected by the action.

before the meeting

purpose_time

Explains why or by when it is necessary.

Formal 文法：B1 語彙：A2 Formal

Must I sign both copies?

Must questions are correct but often formal, official, or serious.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

Must I sign

formal_obligation_question

Asks about obligation with must; this sounds formal or serious.

ひとまとまりで覚える

both copies

object

Names what may be required.

Contrast 文法：A2 語彙：A2 Neutral

Do I have to sign both copies?

This is more common in everyday speech than Must I sign both copies?

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

Do I have to sign

common_obligation_question

The everyday way to ask whether something is required.

ひとまとまりで覚える

both copies

object

Names what may be required.

Usage rules

Negatives: no need or no permission

Negative forms change the meaning sharply. Don't have to and don't need to mean there is no necessity; the action is optional. You don't have to answer every question. He doesn't need to come to the meeting. Needn't has the same no-necessity meaning, but it is less common or more formal in everyday speech. Must not or mustn't means prohibition: You must not park here. Shouldn't means advice not to do something: You shouldn't text while driving. Do not confuse no necessity with no permission. If parking is forbidden, You don't have to park here is the wrong message; it means parking here is not required.

Negative 文法：A2 語彙：A2 Neutral

You don't have to answer every question.

Don't have to means no necessity, not prohibition.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

don't have to answer

no_necessity

Means the action is not required.

ひとまとまりで覚える

every question

scope

Shows what is optional.

Negative 文法：A2 語彙：A1 Neutral

He doesn't need to come to the meeting.

Doesn't need to is another common way to say something is not necessary.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

doesn't need to come

no_necessity

Means coming is not necessary.

ひとまとまりで覚える

to the meeting

destination

Names the event.

Negative 文法：A2 語彙：A1 Formal

You must not park here.

Must not means prohibition, not lack of necessity.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

must not park

prohibition

Means parking is forbidden.

ひとまとまりで覚える

here

place

Gives the place where the rule applies.

Negative 文法：A2 語彙：A2 Neutral

You shouldn't text while driving.

Shouldn't gives advice against an action; it is usually softer than must not.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

shouldn't text

negative_advice

Gives advice not to do something.

ひとまとまりで覚える

while driving

time_condition

Says when the advice applies.

Mistake 文法：A2 語彙：A1 Neutral

You don't have to park here.

This is the wrong message if you mean parking is forbidden; it means parking here is not required.

Corrected 文法：A2 語彙：A1 Formal

You must not park here.

Use must not, can't, or not allowed to for prohibition.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

must not park

prohibition

Correctly expresses that parking is forbidden.

ひとまとまりで覚える

here

place

Gives the place where the rule applies.

Contrast

Should and ought to

Should is the normal verb for advice. Ought to means almost the same thing, but it is less common and can sound a little formal or moral: You ought to apologize. Use should + base verb, but ought to + base verb. The negative shouldn't is common; ought not to is correct but less frequent. Questions with should are normal, while question forms with ought to are formal. Should and ought to can also express expectation, not advice: The package should arrive tomorrow. She ought to be home by now.

Formal 文法：B1 語彙：A2 Neutral

You ought to apologize.

Ought to is close to should, but it is less common and can sound more formal.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

ought to apologize

moral_advice

Gives advice with a slightly formal or moral tone.

ひとまとまりで覚える

Core 文法：B1 語彙：A2 Neutral

The package should arrive tomorrow.

Should can express expectation when the speaker thinks something is likely.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

should arrive

expected_result

Shows an expected result, not advice.

ひとまとまりで覚える

tomorrow

time

Adds when the result is expected.

Core 文法：B1 語彙：A2 Neutral

She ought to be home by now.

Ought to can also express expectation, especially when something seems reasonable or normal.

意味のかたまり

単語ごとではなく、意味のかたまりで文を読んでみましょう。

ought to be home

expected_situation

Shows an expected situation with ought to.

ひとまとまりで覚える

by now

time

Means before or at this time.

Danger zone

Had better is a warning

Had better + base verb gives urgent advice with a possible bad result if it is ignored. It is usually about a specific situation now or soon, not a general habit: You'd better save the file now. The negative is had better not: You'd better not be late. The had is often shortened to 'd and does not make the meaning past. Do not add to after better. Wrong: You had better to save the file now. Correct: You had better save the file now. Questions with had better are uncommon; use should when you simply want advice.

Summary

Function map

Choose the expression by function. For strong obligation, use have to for most everyday duties and must for strong, official, or strongly stressed rules. For practical necessity, use need to. For no necessity, use don't have to or don't need to. For prohibition, use must not, can't, or not allowed to. For advice or expectation, use should; choose ought to when a slightly formal tone is acceptable. For urgent warning advice, use had better, especially with I, we, or close relationships.

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Obligation and advice

Obligation and advice: the pressure dial

Choice, pressure, and advice

意味のかたまり

意味のかたまり

A pressure dial

Core frames

意味のかたまり

意味のかたまり

意味のかたまり

意味のかたまり

Must, have to, and need to

意味のかたまり

意味のかたまり

意味のかたまり

意味のかたまり

意味のかたまり

Negatives: no need or no permission

意味のかたまり

意味のかたまり

意味のかたまり

意味のかたまり

意味のかたまり

Should and ought to

意味のかたまり

意味のかたまり

意味のかたまり

Had better is a warning

Function map

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