Grammar Rule in 30 Seconds
Use 'Modal + be + Past Participle' to focus on what happens to an object when using words like can, must, or should.
- Always use 'be' in its base form after the modal: 'It can be fixed' (not 'is fixed').
- The main verb must be a past participle: 'The work should be done' (not 'do' or 'did').
- For negatives, put 'not' between the modal and 'be': 'It cannot be opened'.
Overview
passive voice with modals（法助動詞を用いた受動態）は、B1レベルの学習者が表現の幅を大きく広げるための非常に重要なステップです。日本語には「受動態」そのものは存在しますが、英語の「法助動詞＋受動態」という組み合わせは、日本語の文法体系とは異なる論理で動いています。この構造をマスターすると、「誰がしたか」という主語をあえて言わずに、「何がどうなる可能性があるのか」「何が求められているのか」という事実に焦点を当てた、客観的で洗練された表現が可能になります。The office must be cleaned（オフィスは掃除されなければならない）という表現は、誰が掃除するかよりも「掃除が必要である」という事実を強調します。日本語の「掃除しなければなりません」という能動的な表現に比べ、英語のこの形は責任の所在をぼかし、より丁寧でプロフェッショナルな響きを持ちます。この感覚を身につけることは、英語で自然なコミュニケーションをとるための鍵となります。be動詞＋過去分詞という形を使います。ここにcanやmustなどの法助動詞が加わると、語順が固定されます。be動詞は、主語が何であっても、時制がどうであっても、常にbeという原形のままになります。これが学習者にとって非常に親切な点です。例えば、The report can be finishedのように、canの後ろにはisやwasではなく、必ずbeが置かれます。これは日本語の「～できる」という助動詞（可能の助動詞）が動詞に直接接続するのと対照的です。英語では助動詞と動詞の間に「役割を果たす要素（be）」を挟み込むことで、意味の重なりを整理しているのです。Subject + Modal Verb + be + Past Participleです。by + Agentは必要に応じて付け加えますが、基本的には省略されることが多いです。The door can be opened. |The form must be signed. |The email should be sent. |The plan might be changed. |beは一切変化しません。日本語では「開けられる」「開けられなければならない」と動詞が複雑に変化しますが、英語ではbeを固定して、後ろの過去分詞を入れ替えるだけで済むため、慣れてしまえば日本語よりもシンプルに感じるはずです。You made a mistake（あなたがミスをした）と言うのは非常に攻撃的です。しかし、The mistake should be corrected（ミスは修正されるべきだ）と言えば、誰を責めるわけでもなく、解決策に焦点を当てることができます。これは日本語の「～しておく必要がありますね」といった婉曲的な表現に近い役割を果たします。All trash must be thrown away（ゴミは捨てられなければならない）という表現は、誰に対して言っているわけでもなく、普遍的なルールとして機能します。これは日本語の「ゴミは捨ててください」よりも、より公的な響きを持ちます。The news might be announced soon（ニュースがまもなく発表されるかもしれない）のように、確信が持てない事柄について、自分個人の意見ではなく、状況に基づいた可能性を述べる際に非常に便利です。日本語の「～されるかもしれませんね」という推測と全く同じ感覚で使えます。- 1
beの脱落:The report can finishedのように、beを忘れるミスです。これは日本語に「be動詞」に相当する単語がないため、頭の中で「助動詞＋過去分詞」と直結させてしまうことが原因です。canとfinishedの間に必ずbeという「橋渡し」が必要だと意識してください。
- 1過去分詞の誤用:
The work must be doのように、過去分詞ではなく動詞の原形を使ってしまうミスです。日本語の「～される」という形に引っ張られ、動詞の形を変化させることを忘れてしまうのです。done,written,sentなど、過去分詞の形をしっかり確認する癖をつけましょう。
- 1主語の不一致: 能動態の感覚で、本来の目的語を主語に置くのを忘れてしまうミスです。
We can finish the report（能動態）とThe report can be finished（受動態）を混同し、The report can finishと言ってしまうことがあります。受動態は「主語が何かをされる」という構造なので、主語と動詞の関係を常に確認する必要があります。
I must clean the room. | 動作主（私） |The room must be cleaned. | 対象物（部屋） |by + agentは必ず必要ですか？byを使うのは、特別な理由がある時だけです。beがisやareになることはありますか？can isやmust areは文法的に完全に誤りです。常にbeの形を保ってください。mightとcouldのどちらを使うべきですか？mightの方がより確信度が低く、控えめな印象を与えます。状況に応じて使い分けましょう。2. Negative Contractions
| Full Form | Contracted Form | Usage |
|---|---|---|
|
cannot be
|
can't be
|
Common in speech
|
|
should not be
|
shouldn't be
|
Common in speech
|
|
must not be
|
mustn't be
|
Common in speech/British English
|
|
will not be
|
won't be
|
Very common
|
|
could not be
|
couldn't be
|
Common in speech
|
|
might not be
|
mightn't be
|
Rare, mostly British
|
Modal Passive Structure
| Subject (Receiver) | Modal Verb | Auxiliary 'be' | Past Participle (V3) |
|---|---|---|---|
|
The work
|
can
|
be
|
done
|
|
The rules
|
must
|
be
|
followed
|
|
The letter
|
should
|
be
|
written
|
|
The house
|
might
|
be
|
sold
|
|
The truth
|
will
|
be
|
known
|
|
The decision
|
may
|
be
|
changed
|
|
The car
|
could
|
be
|
fixed
|
|
The laws
|
ought to
|
be
|
obeyed
|
Meanings
A grammatical construction used to express modality (possibility, necessity, obligation) while keeping the focus on the person or thing receiving the action rather than the one performing it.
Possibility/Ability
Expressing that an action is possible for the object.
“The problem can be solved easily.”
“A solution might be found soon.”
Obligation/Necessity
Expressing that an action is required or mandatory for the object.
“The law must be obeyed.”
“The taxes have to be paid by Friday.”
Permission/Prohibition
Expressing what is allowed or forbidden regarding the object.
“Phones may not be used during the exam.”
“The room can be rented for parties.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Obj + Modal + be + V3
|
The cake will be eaten.
|
|
Negative
|
Obj + Modal + not + be + V3
|
The cake won't be eaten.
|
|
Question
|
Modal + Obj + be + V3?
|
Will the cake be eaten?
|
|
Short Answer (+)
|
Yes, Obj + Modal.
|
Yes, it will.
|
|
Short Answer (-)
|
No, Obj + Modal + not.
|
No, it won't.
|
|
With 'By' Agent
|
Obj + Modal + be + V3 + by...
|
The cake will be eaten by us.
|
|
Past Modal Passive
|
Obj + Modal + have been + V3
|
The cake should have been eaten.
|
フォーマル度スペクトル
The report must be submitted by 5 PM. (Workplace deadline)
The report needs to be handed in by 5. (Workplace deadline)
The report's gotta be done by 5. (Workplace deadline)
Get that report in by 5, no cap. (Workplace deadline)
The Modal Passive Universe
Possibility
- Can be Ability
- Might be Uncertainty
Obligation
- Must be Strong necessity
- Should be Advice
Permission
- May be Formal permission
- Can be Informal permission
Active vs. Passive Modals
Is it Modal Passive?
Is there a modal (can, must, etc.)?
Is the focus on the receiver?
Did you add 'be'?
Common Past Participles for Passive
Regular
- • Finished
- • Cleaned
- • Fixed
- • Opened
Irregular
- • Done
- • Written
- • Seen
- • Taken
- • Broken
レベル別の例文
The window can be opened.
It is possible to open the window.
The food must be hot.
The food needs to be hot.
The book can be read.
It is possible to read the book.
The car must be clean.
The car needs to be clean.
The room should be cleaned every day.
It is a good idea to clean the room daily.
The email can be sent now.
You are able to send the email now.
The door must not be locked.
Do not lock the door.
Can the bill be paid by credit card?
Is it possible to pay with a card?
The application must be submitted by Friday.
You are required to hand in the application by Friday.
The results might be announced tomorrow.
There is a chance they will tell us the results tomorrow.
This software can be downloaded for free.
You are able to get this software without paying.
The meeting should be rescheduled.
I suggest we change the time of the meeting.
The project ought to be completed ahead of schedule.
It is expected that the project will finish early.
Such behavior will not be tolerated in this office.
We will not allow this kind of behavior.
The data could be interpreted in several ways.
There are different ways to understand the data.
The contract may be terminated with 30 days' notice.
Either party can end the contract if they give notice.
It could be argued that the policy was a failure.
One might make the argument that the policy failed.
The implications must be carefully considered.
We need to think very deeply about the consequences.
No part of this book may be reproduced without permission.
You are not allowed to copy this book.
The witness should be questioned further.
It is necessary to ask the witness more questions.
The nuances of the text might be overlooked by a casual reader.
A normal reader might not notice the small details.
It is imperative that the status quo be maintained.
It is absolutely necessary that things stay as they are.
The debt shall be repaid in full by the end of the fiscal year.
The debt must be paid back completely.
The truth of the matter can only be surmised.
We can only guess what the truth is.
間違えやすい
Learners often use the active form when they mean the passive because it's simpler.
They mean the same thing, but 'have to' conjugates like a normal verb.
Learners confuse 'be doing' with 'be done'.
よくある間違い
It can done.
It can be done.
It must be do.
It must be done.
The car can be fix.
The car can be fixed.
Must be the door closed?
Must the door be closed?
It should be not opened.
It should not be opened.
The letters can been sent.
The letters can be sent.
He can be tell.
He can be told.
The work must is done.
The work must be done.
It might be can fixed.
It might be fixed.
The house should be sell.
The house should be sold.
The task needs be done.
The task needs to be done.
It may be being processed.
It may be processed.
文型パターン
The ___ must be ___ by ___.
It can be ___ easily.
___ should not be ___ without ___.
How can the ___ be ___?
Real World Usage
The successful candidate will be notified by email.
Hard hats must be worn on this site.
This issue can be resolved by restarting your device.
The mixture should be stirred until smooth.
This agreement may be modified only in writing.
Your account might be suspended if you break the rules.
The 'By' Test
Don't conjugate 'be'
Polite Complaints
Formal vs Informal
Smart Tips
Use 'should be' or 'could be' to make requests. It sounds less like a command.
Check if there is a modal before it. If so, you are looking at a modal passive!
Always use the 'third form' from your verb list (e.g., go-went-GONE).
Use 'must be' + V3. It is the standard way to express non-negotiable requirements.
発音
The 'be' reduction
In natural speech, the word 'be' is often unstressed and sounds like a quick /bi/ or even /bə/.
Modal + not contraction
Contractions like 'can't' or 'won't' are much more common than 'cannot' or 'will not' in spoken English.
Emphasis on the Modal
It MUST be done!
Conveys strong urgency or insistence.
Emphasis on the Participle
It can be FIXED.
Conveys that the action is possible, even if difficult.
暗記しよう
記憶術
Remember 'MBP': Modal + Be + Participle. It's the 'Most Basic Passive' formula.
視覚的連想
Imagine a robot on an assembly line. The robot doesn't care who built it, only that it 'must be built'. See the word 'BE' glowing in the middle of the robot's chest.
Rhyme
If a modal is what you see, don't forget the little word 'be'!
Story
A detective arrives at a crime scene. He doesn't know who did it, so he says: 'The door must be opened, the fingerprints must be taken, and the truth will be found.' He focuses on the actions because the 'who' is a mystery.
Word Web
チャレンジ
Look around your room. Find 3 things and say what 'must be done' to them (e.g., 'The bed must be made', 'The window should be cleaned').
文化メモ
British speakers use 'mustn't be' more frequently than Americans, who often prefer 'shouldn't be' or 'can't be' for prohibitions.
The modal passive is used to avoid 'blame culture'. Instead of saying 'You didn't finish the report,' a manager says 'The report should have been finished,' focusing on the task.
Legal documents use 'shall be' to indicate a binding obligation, which is rarely used in everyday speech.
The passive voice in English evolved from Old English using 'weorthan' (to become) and 'beon' (to be). Modals were originally independent verbs that gradually became auxiliaries.
会話のきっかけ
What is one thing in your city that should be improved?
Do you think AI can be used to replace teachers?
What rules must be followed in your workplace?
If you were president, what laws would be changed?
日記のテーマ
よくある間違い
Test Yourself
The application form must ___ (sign) by the applicant.
Which sentence is correct?
Find and fix the mistake:
The secret should not be tell to anyone.
Active: You must wash this shirt by hand.
In the modal passive, the word 'be' changes to 'is' if the subject is singular (e.g., 'He').
A: Can I take this book home? B: No, it ___.
Select the valid structure:
Match each item on the left with its pair on the right:
Score: /8
練習問題
8 exercisesThe application form must ___ (sign) by the applicant.
Which sentence is correct?
Find and fix the mistake:
The secret should not be tell to anyone.
Active: You must wash this shirt by hand.
In the modal passive, the word 'be' changes to 'is' if the subject is singular (e.g., 'He').
A: Can I take this book home? B: No, it ___.
Select the valid structure:
Match 'We can solve it' with its passive form.
Score: /8
Practice Bank
12 exercisesThis email ___ sent to the wrong person. Please retrieve it.
The new rules must explained clearly.
Choose the correct sentence:
Translate into English: 'El trabajo puede ser completado mañana.'
Arrange these words into a sentence:
Match the modals with their passive constructions:
These delicate items ___ handled with care.
Our flight could be delay due to the storm.
Translate into English: 'Las noticias serán anunciadas pronto.'
Arrange these words into a sentence:
Which of the following sentences is grammatically correct?
Connect the modals to their suitable passive completions:
Score: /12
よくある質問 (8)
Yes, in informal English you can say 'It might get done,' but 'be' is much more common and safer for B1 learners.
English doesn't allow two modals together. You can't say 'It might can be done.' Use 'It might be possible to do it' instead.
No, in fact, we usually omit it if the person doing the action is obvious or not important.
Move the modal to the front: 'Can it be fixed?' or 'Should the meeting be moved?'
Because modal verbs are always followed by the base form of the next verb. The base form of 'is/am/are' is `be`.
Most can (can, could, must, should, may, might, will, would). 'Shall' is rare but possible in legal texts.
Technically, 'have to' is a semi-modal, but it follows the same passive pattern: 'have to + be + V3'.
Avoid it in very casual conversation with friends, as it can sound too formal or 'robotic'.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
puede ser + participio / se puede + infinitivo
English always requires the auxiliary 'be', whereas Spanish often uses the reflexive 'se'.
peut être + participe passé
French participles must agree in gender and number with the subject, unlike English.
kann ... werden + Partizip II
The auxiliary 'werden' and the modal create a 'verb bracket' where the participle goes to the very end of the sentence.
〜れる / 〜られる (passive suffix) + modal
Japanese doesn't use a separate 'be' verb; the passive is built into the main verb's conjugation.
Passive verb form + modal (yumkin/yajib)
There is no equivalent to the English 'be' auxiliary in Arabic passive constructions.
可以被 (kěyǐ bèi) + verb
Chinese verbs do not change form (no past participle), so the 'V3' concept is entirely new to Chinese learners.
Learning Path
Prerequisites
Learn These First
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