Grammar Rule in 30 Seconds
Use 'by' in passive sentences to mention who or what performed the action while keeping the focus on the result.
- Place 'by' after the past participle to introduce the doer: 'The song was sung by Adele.'
- Only use 'by' if the person or thing doing the action is important information.
- Don't confuse 'by' (the doer) with 'with' (the tool used): 'The door was opened by John with a key.'
Overview
The evidence was discovered by a local farmer と言うのを耳にしたことがあるかもしれません。この小さな by という言葉は、英語において非常に強力な役割を果たします。これを使うことで、受動態を使いながらも、誰がその行為を行ったのかを明確に示すことができます。通常、受動態は「誰がやったか」を隠すマスクのようなものですが、時には「行為そのもの」が重要でありつつも、その背後にいる人物を無視できない（あるいは功績を称えたい、あるいは罪を着せたい）場合があります。そこで登場するのが by + 行為者（エージェント）のパターンです。これは、結果を強調したいけれど、作成者にも言及する必要がある場合の完璧な架け橋となります。このガイドでは、B1レベルの流暢さを目指し、自然でプロフェッショナルな文の作り方を学びます。How This Grammar Works
My pizza was eaten by my roommate. 行為者は、単に行為を行った人や物です。by の後に行為者を置くことで、焦点が変わります。ピザ（被害者）が文の主語になります。これは、結果が人物よりも興味深い場合や、特定の文のリズムを作りたい場合に非常に便利です。何かに責任を転嫁したいときにも使えますが、あまり使いすぎると、壊れた花瓶の責任から逃れようとしているロボットのように聞こえてしまうので注意しましょう。
Formation Pattern
to be の適切な形を加えます。これは時制に合わせて変化します。
by を加えます。
When To Use It
A cure was discovered by scientists となるでしょう。第二に、芸術的なクレジット。曲、本、映画ではほぼ常にこれが使われます：The Great Gatsby was written by F. Scott Fitzgerald. 第三に、サスペンスを演出するとき。ミステリー小説では The door was opened by a shadow といった表現が使われます。最後に、誰かを直接責めるのを避けたいけれど、言及は必要なとき。The glass was broken by Jim は「ジムがグラスを割った！」と言うよりも少し攻撃性が低く感じられます。
Common Mistakes
by の代わりに with を使ってしまうことです。覚えておいてください：by は人（行為者）のため、with は道具（手段）のためです。The letter was written with Shakespeare とは言いません。それだと彼をペンとして使ったことになってしまいます。また、動詞 to be を忘れるのもよくあるミスです。The photo taken by me は文ではありません。The photo was taken by me とする必要があります。代名詞にも注意しましょう！行為者が代名詞の場合、目的格にする必要があります。by him, by her, by them とします。最後に、行為者を使いすぎないこと。「誰か」や「人々」が行為者の場合は、省略するのが普通です。Contrast With Similar Patterns
by + 行為者 と with + 道具 を混同しやすいです。前述の通り、by は「誰が？」に答え、with は「何の道具で？」に答えます。例えば：The cake was cutまた、行為者のない受動態とも比較しましょう。ほとんどの受動態は行為者を必要としません。by the chef(行為者)with a silver knife(道具).
My bike was stolenは、誰がやったか分からないので、それだけで完結しています。
by + 行為者 は、その情報が価値を加えたり、クレジットが必要な場合にのみ追加します。Quick FAQ
常に行為者を含める必要がありますか？
いいえ！興味深い、重要、あるいは驚くべき場合のみ含めてください。
人だけでなく物にも by を使えますか？
はい！
The town was destroyed by the storm. のように使えます。
このパターンは会話と書き言葉、どちらで一般的ですか？
フォーマルな書き言葉でよく見かけますが、強調のために会話でもよく使われます。
Passive Voice with 'By' Across Tenses
| Tense | Subject | Verb 'Be' | Past Participle | By + Agent |
|---|---|---|---|---|
|
Present Simple
|
The reports
|
are
|
written
|
by the staff.
|
|
Past Simple
|
The report
|
was
|
written
|
by the manager.
|
|
Present Continuous
|
The report
|
is being
|
written
|
by the intern.
|
|
Past Continuous
|
The report
|
was being
|
written
|
by Sarah.
|
|
Present Perfect
|
The report
|
has been
|
written
|
by the team.
|
|
Future (Will)
|
The report
|
will be
|
written
|
by the director.
|
|
Modals
|
The report
|
must be
|
written
|
by you.
|
Meanings
The passive voice with 'by' is used to identify the 'agent' (the person or thing that performs the action) when the sentence structure is passive. It allows the speaker to emphasize the receiver of the action while still providing credit or responsibility to the doer.
Artistic & Intellectual Credit
Used to attribute books, paintings, songs, or inventions to their creators.
“This novel was written by George Orwell.”
“The symphony was composed by Beethoven.”
Official & Legal Responsibility
Used in news or legal documents to state who performed an official action.
“The law was passed by the parliament.”
“The decision was made by the CEO.”
Unexpected Agents
Used when the doer of the action is surprising or particularly noteworthy.
“The window was broken by a falling branch.”
“The cake was eaten by the dog!”
Reference Table
| 構造 | 例 | 意味 | いつ使うか |
|---|---|---|---|
|
能動態
|
Sarah wrote the report.
|
サラ（行為者）が行動した。
|
行為者に焦点を当てる時。
|
|
受動態（行為者なし）
|
The report was written.
|
レポート（受け手）が行動を受けた。
|
行為者が不明／重要でない時。
|
|
受動態（'by'あり）
|
The report was written by Sarah.
|
レポート（受け手）が行動を受け、サラが行為者。
|
行為者が重要／功績を称える時。
|
|
現在単純受動態
|
The coffee is brewed by her.
|
彼女がコーヒーを淹れる。
|
習慣的な行動、功績を称える時。
|
|
過去単純受動態
|
The song was sung by him.
|
彼がその歌を歌った。
|
過去の行動、功績／特定する時。
|
|
未来単純受動態
|
The project will be managed by them.
|
彼らがプロジェクトを管理するだろう。
|
将来の計画、割り当て。
|
フォーマル度スペクトル
The manuscript was authored by an unknown scholar. (Literature)
The book was written by a local author. (Literature)
It was written by some guy I know. (Literature)
This was penned by my homie. (Literature)
受動態：「By」と行為者 コンセプトマップ
構造
- Subject + Be + V3 + by + Agent 形成
- Be (conjugated) 助動詞
- Past Participle (V3) 動詞の形
いつ使うか
- 功績／責任を帰する 責任を割り当てる
- 重要／予期せぬ行為者 実行者を強調する
- フォーマルな文脈 客観的なトーン
- 明瞭さ 曖昧さをなくす
重要な区別
- By (Agent) 行動をする人や物
- With (Instrument) 行動に使われる道具
- byを省略する（重要でない場合） 実行者は不要
例
- was written by Sarah 執筆の功績
- is designed by Apple 行為者としての企業
- will be delivered by drone 方法／行為者
受動態における by と with の比較
「By + 行為者」を使うべきですか？
その文は受動態ですか？
行為者（実行者）は既知ですか、それとも重要ですか？
その「行為者」は実際には道具／手段ですか？
受動態の文における行為者
人々
- • The book was read by a student.
- • The meal was prepared by the chef.
組織
- • The car was manufactured by Tesla.
- • The software was developed by Google.
動物
- • The food was eaten by the dog.
- • The sheep were herded by the dog.
力／原因
- • The tree was struck by lightning.
- • The bridge was damaged by the earthquake.
レベル別の例文
The book was written by him.
El libro fue escrito por él.
The cake was made by my dad.
El pastel fue hecho por mi papá.
The car was washed by Sam.
El coche fue lavado por Sam.
The photo was taken by her.
La foto fue tomada por ella.
The window was broken by a ball.
La ventana fue rota por una pelota.
The songs were sung by a famous choir.
Las canciones fueron cantadas por un coro famoso.
The house was built by my grandfather in 1950.
La casa fue construida por mi abuelo en 1950.
The emails were sent by the secretary.
Los correos fueron enviados por la secretaria.
The new law was signed by the President yesterday.
La nueva ley fue firmada por el Presidente ayer.
The bridge was designed by a French architect.
El puente fue diseñado por un arquitecto francés.
The missing child was found by a local hiker.
El niño desaparecido fue encontrado por un excursionista local.
The dinner was prepared by a professional chef.
La cena fue preparada por un chef profesional.
The experiment was conducted by a team of researchers from Oxford.
El experimento fue realizado por un equipo de investigadores de Oxford.
The company was founded by two brothers in their garage.
La empresa fue fundada por dos hermanos en su garaje.
The mural was painted by an anonymous artist overnight.
El mural fue pintado por un artista anónimo durante la noche.
The decision was heavily criticized by the local media.
La decisión fue fuertemente criticada por los medios locales.
The initiative was spearheaded by a coalition of environmental NGOs.
La iniciativa fue encabezada por una coalición de ONGs ambientales.
The manuscript was discovered by chance by a young librarian.
El manuscrito fue descubierto por casualidad por un joven bibliotecario.
The city's infrastructure was severely damaged by the hurricane.
La infraestructura de la ciudad fue gravemente dañada por el huracán.
The role was originally intended to be played by a younger actor.
El papel estaba originalmente destinado a ser interpretado por un actor más joven.
The silence was eventually broken by the rhythmic ticking of the clock.
El silencio fue finalmente roto por el tictac rítmico del reloj.
The policy was implemented by the government in the face of mounting public pressure.
La política fue implementada por el gobierno ante la creciente presión pública.
The intricate patterns were woven by hand by artisans in the remote village.
Los intrincados patrones fueron tejidos a mano por artesanos en la remota aldea.
The verdict was reached by the jury after three days of deliberation.
El veredicto fue alcanzado por el jurado tras tres días de deliberación.
間違えやすい
Learners use 'by' for tools and 'with' for people.
In many languages, the word for 'from' is used for the passive agent.
Learners say 'He is known by everyone.'
よくある間違い
The book was written from Mark.
The book was written by Mark.
The cake was make by Mom.
The cake was made by Mom.
The car was wash by Sam.
The car was washed by Sam.
It was by him written.
It was written by him.
The window was broken by a hammer.
The window was broken with a hammer.
The song was sang by her.
The song was sung by her.
The letter was by me sent.
The letter was sent by me.
The house was built of my father.
The house was built by my father.
The decision was made by the meeting.
The decision was made at the meeting.
He was known by everyone.
He was known to everyone.
The room was filled by smoke.
The room was filled with smoke.
文型パターン
The ___ was ___ by ___.
Has the ___ been ___ by ___ yet?
The ___ is being ___ by ___ right now.
It is believed that the ___ was ___ by ___.
Real World Usage
This sculpture was created by a local artist.
The bank was robbed by three masked men.
Photo by @TravelGuru.
The project was managed by me and two colleagues.
The pyramids were built by thousands of workers.
Your ticket is being handled by our senior engineer.
行為者が重要！
by と with の違い
焦点を忘れずに！
フォーマルな場面で活躍！
代名詞の形をチェック！
Smart Tips
Always use 'by' to credit the creator. It's the most natural way to speak in English.
Pause and check if you should use 'with' instead of 'by'.
Put it at the end of the sentence with 'by' to make the sentence easier to read.
Ask yourself: 'Is it important to know who did this?' If no, delete the 'by' phrase.
発音
The 'By' Connection
The word 'by' is usually unstressed. It sounds like /baɪ/ but is said very quickly, linking the verb to the agent.
End-Focus
The book was written by SHAKESPEARE. ↘
The stress often falls on the agent at the end of the sentence because it is the new information.
暗記しよう
記憶術
B.Y. stands for 'Behold the Yesterday-doer' — it brings the person from the past action back to the end of the sentence.
視覚的連想
Imagine a movie poster where the title is huge at the top (the Object), and the director's name is in small letters at the bottom after the word 'By'. The focus is the movie, but the credit is at the end.
Rhyme
When the action is done and the object is first, use 'by' for the person or the bubble will burst!
Story
A famous painting was stolen from a museum. The news said 'The painting was taken' (Passive). Everyone asked 'Who?'. The news updated: 'The painting was taken BY a clever thief.' The 'by' solved the mystery.
Word Web
チャレンジ
Look around your room. Find three items and say who they were made or bought by. (e.g., 'This lamp was bought by my sister.')
文化メモ
In Western academic writing, the passive with 'by' is used to show objectivity. However, modern styles (like APA) now encourage the active voice ('We found that...') to be more direct.
The BBC and other UK news outlets frequently use the passive with 'by' to report crimes or official statements to avoid sounding biased.
In galleries worldwide, 'by' is the standard way to attribute work. You will almost never see 'from' or 'of' on a painting's label.
The use of 'by' to indicate an agent comes from Old English 'be', which originally meant 'near' or 'at'. Over time, it evolved to mean 'through the agency of'.
会話のきっかけ
What is your favorite book, and who was it written by?
Think of a famous invention. Who was it invented by?
Was your house built by a company or an individual?
If your life were a movie, who would it be directed by?
日記のテーマ
よくある間違い
Test Yourself
The famous novel was written ___ an acclaimed author.
Find and fix the mistake:
The delicious pizza was eaten with my brother.
Choose the correct sentence:
Translate into English: 'La presentación fue dada por la profesora.'
Answer starts with: ["T...
Score: /4
練習問題
8 exercisesThe letter was written ___ a fountain pen ___ my grandfather.
Which sentence correctly gives credit to the artist?
Find and fix the mistake:
The cake was eaten from the dog.
Active: 'Steve Jobs founded Apple.'
Match the following:
broken / by / was / window / the / him
You must always use 'by' in every passive sentence.
A: Who fixed your computer? B: It ___ by my brother.
Score: /8
Practice Bank
14 exercisesThis famous cathedral ___ built ___ hundreds of workers.
The delicious cake was baked by a special recipe.
Which sentence is correct?
Translate into English: 'El problema fue resuelto por mi colega.'
Arrange these words into a sentence:
Match the sentences:
The decision has already ___ made ___ the committee.
The new rules was announced by the principal.
Choose the correct sentence:
Translate into English: 'El trabajo de casa fue terminado por todos los estudiantes.'
Arrange these words into a sentence:
Match the fragments:
Many classic novels ___ still read ___ students today.
The new software is being developed by a small team of engineers now.
Score: /14
よくある質問 (8)
Don't use `by` if the agent is obvious (e.g., 'He was arrested'), unknown (e.g., 'My bike was stolen'), or unimportant (e.g., 'The road was paved').
Yes, but it's rare. Usually, we use the specific noun or a person's name. 'The window was broken by it' is grammatically correct but 'The window was broken by the wind' is better.
The passive voice itself is often formal, but adding `by` is just a way to provide information. It can be used in both formal and informal contexts.
Use `by` for the person or force that does the action. Use `with` for the tool or object used to do it. 'The tree was cut by the lumberjack with an axe.'
Absolutely. 'The office is cleaned by a professional crew every night.'
In creative writing, 'by' can make sentences feel long and slow. However, in academic and technical writing, it is essential for accuracy.
Yes. 'He got caught by the police.' This is more informal than 'He was caught by the police.'
Usually, yes. However, you can add time phrases after it: 'The book was written by him in 1990.'
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
por
Spanish speakers might confuse 'by' with 'for' because 'por' can mean both.
par
French sometimes uses 'de' for states (e.g., 'aimé de tous'), whereas English usually sticks to 'by' or 'to'.
von
German word order is much more flexible, often placing the 'von' phrase before the verb.
ni / ni yotte
Japanese passives often imply that the subject is 'adversely affected' by the action, which English doesn't necessarily do.
min qibal
In Arabic, it is often considered stylistically better to avoid mentioning the agent in a passive sentence.
bèi
In Chinese, the 'bèi' structure is traditionally used for negative or unpleasant events, though this is changing in modern usage.
Learning Path
Prerequisites
Learn These First
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