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When to mention or omit the agent using by.
Practice: build the sentences →The agent is the person, group, or thing that performs the action expressed by a passive verb.
In passive sentences, the agent can be introduced with by, but it is often omitted when it is unknown, obvious, unimportant, or intentionally not mentioned.
The novel was written by George Orwell.
Роман был написан Джорджем Оруэллом.
Agent introduced with "by".
My car was stolen.
Мою машину украли.
Agent omitted because unknown.
The road is being repaired.
Дорога ремонтируется.
Agent omitted because irrelevant.
Use by to introduce the agent that performs the action in a passive sentence.
For example, The novel was written by George Orwell and The decision was made by the committee.
The novel was written by George Orwell.
Роман был написан Джорджем Оруэллом.
By + agent.
The decision was made by the committee.
Решение было принято комитетом.
By + organization.
The song was performed by a famous singer.
Песня была исполнена известным певцом.
By + agent.
The agent is commonly omitted when the identity of the person performing the action is unknown, obvious, irrelevant, or unimportant.
For example, My car was stolen and The road is being repaired.
My car was stolen.
Мою машину украли.
Agent unknown.
The road is being repaired.
Дорога ремонтируется.
Agent irrelevant.
The window was broken.
Окно было разбито.
Agent unknown.
Omit the agent when the person or thing responsible for the action is not known.
For example, The window was broken during the night.
The window was broken during the night.
Окно было разбито ночью.
Agent unknown.
My bike was stolen from the garage.
Мой велосипед украли из гаража.
Agent unknown.
The agent can be omitted when the context makes it obvious who performed the action.
For example, The suspect was arrested after the attack. The identity of the police officers may be obvious from the context.
The suspect was arrested after the attack.
Подозреваемый был арестован после нападения.
Agent obvious: police.
The patient was treated immediately.
Пациента немедленно пролечили.
Agent obvious: medical staff.
The agent can be omitted when the action or result is more important than who performed it.
For example, The new bridge was completed last month focuses on the bridge and its completion rather than the workers.
The new bridge was completed last month.
Новый мост был завершён в прошлом месяце.
Focus on the bridge, not the workers.
The package was delivered on time.
Посылка была доставлена вовремя.
Focus on delivery, not the courier.
A speaker or writer may deliberately omit the agent when assigning responsibility is undesirable, unnecessary, or not relevant.
For example, Mistakes were made can avoid explicitly identifying who was responsible.
Mistakes were made.
Были допущены ошибки.
Agent intentionally omitted to avoid assigning blame.
The matter will be looked into.
Этот вопрос будет рассмотрен.
Agent intentionally backgrounded.
Agents expressed by general nouns such as people, someone, they, or the public are often omitted when the passive sentence remains clear without them.
For example, English is spoken all over the world is more natural than English is spoken by people all over the world.
English is spoken all over the world.
На английском говорят по всему миру.
Generic agent "people" omitted.
The rules must be followed.
Правила должны соблюдаться.
Generic agent omitted.
Formal and academic writing often omits agents when the process or result is more important than the person performing the action.
For example, The samples were collected and The results were analyzed are common scientific constructions.
The samples were collected.
Образцы были собраны.
Formal/scientific: agent omitted.
The results were analyzed.
Результаты были проанализированы.
Process focus.
Include the agent when identifying who performed the action is important to the meaning, contrast, or purpose of the sentence.
For example, The painting was created by Picasso distinguishes the creator from other possible artists.
The painting was created by Picasso.
Картина была создана Пикассо.
Agent important for identification.
The decision was made by the committee.
Решение было принято комитетом.
Agent relevant for accountability.
The agent performs an action, while an instrument is the means or tool used to perform it.
For example, The window was broken by the boy identifies the agent, while The window was broken with a hammer identifies the instrument.
The window was broken by the boy.
Окно было разбито мальчиком.
By + agent (person).
The window was broken with a hammer.
Окно было разбито молотком.
With + instrument.
By commonly introduces an agent, while with commonly introduces an instrument, material, or means.
Compare The cake was made by Sarah with The cake was cut with a knife.
The cake was made by Sarah.
Торт был приготовлен Сарой.
By + agent.
The cake was cut with a knife.
Торт был разрезан ножом.
With + instrument.
The agent introduced by by can be an organization, institution, government, company, or other collective entity.
For example, The policy was introduced by the government and The software was developed by the company.
The policy was introduced by the government.
Политика была введена правительством.
By + institution.
The software was developed by the company.
Программное обеспечение было разработано компанией.
By + company.
By can sometimes introduce a natural force or other cause conceptualized as the source of an event.
For example, The trees were damaged by the storm.
The trees were damaged by the storm.
Деревья были повреждены штормом.
By + natural force.
The crops were destroyed by the frost.
Урожай был уничтожен морозом.
By + natural cause.
Pronouns used after by normally take object forms.
For example, The message was sent by him and The decision was made by us.
The message was sent by him.
Сообщение было отправлено им.
Object pronoun after by.
The decision was made by us.
Решение было принято нами.
Object pronoun after by.
A by-phrase can contain a noun phrase with modifiers and coordination.
For example, The project was approved by the senior management team and The decision was made by John and Sarah.
The project was approved by the senior management team.
Проект был одобрен высшим руководством.
By + compound noun phrase.
The decision was made by John and Sarah.
Решение было принято Джоном и Сарой.
By + coordinated agents.
The by-phrase normally follows the passive verb and its required complements.
For example, The book was written by a well-known author and The problem was solved by the engineering team.
The book was written by a well-known author.
Книга была написана известным автором.
By-phrase after verb.
The problem was solved by the engineering team.
Проблема была решена инженерной командой.
By-phrase at end.
In complex passive sentences, the agent may appear later in the sentence to keep the main information easier to process.
For example, The proposal, which had been discussed for several months, was finally approved by the board.
The proposal, which had been discussed for several months, was finally approved by the board.
Предложение, которое обсуждалось несколько месяцев, было наконец одобрено советом директоров.
Agent appears later in a complex passive sentence.
The manuscript, after being reviewed by several experts, was accepted for publication.
Рукопись, после того как её рассмотрели несколько экспертов, была принята к публикации.
Agent in a later position.
Technical writing often omits the agent because the procedure or result is more important than the person who performs it.
For example, The solution was heated to 80°C and The samples were then examined under a microscope.
The solution was heated to 80°C.
Раствор был нагрет до 80°C.
Agent omitted; process focus.
The samples were then examined under a microscope.
Затем образцы были исследованы под микроскопом.
Agent omitted; procedure focus.
Whether the agent is expressed depends on what information the speaker or writer wants to foreground.
The passive can place the affected person, thing, or process in subject position while moving the agent into a less prominent position.
The report was written by the intern.
Отчёт был написан стажёром.
Agent is new or important information.
The report was written yesterday.
Отчёт был написан вчера.
Agent omitted; result/time foregrounded.
An agent is especially useful when contrasting who performed similar or different actions.
For example, The first experiment was conducted by Smith, while the second was conducted by Jones.
The first experiment was conducted by Smith, while the second was conducted by Jones.
Первый эксперимент был проведён Смитом, а второй — Джонсом.
Contrasting agents.
The novel was written by Tolstoy, not by Dostoevsky.
Роман был написан Толстым, а не Достоевским.
Contrasting agents.
Omitting the agent can make responsibility less explicit or allow attention to remain on the event or result.
This is common in institutional, political, and formal language where the identity of the responsible party may be backgrounded.
Mistakes were made.
Были допущены ошибки.
Agent omitted to avoid assigning responsibility.
The funds were misappropriated.
Средства были присвоены.
Agent backgrounded.
Passive constructions containing reporting or causative patterns may include or omit an agent according to the intended focus.
For example, The decision is believed to have been made by the committee places the agent in a secondary position.
The decision is believed to have been made by the committee.
Считается, что решение было принято комитетом.
Agent in a passive reporting structure.
The building is said to have been designed by a famous architect.
Говорят, что здание было спроектировано известным архитектором.
Agent in a passive reporting structure.
Mention the agent when it adds meaningful information; omit it when it is unknown, predictable, irrelevant, or intentionally backgrounded.
The choice should be based on communicative purpose rather than on a fixed rule that passive sentences should always omit the agent.
The window was broken by the storm.
Окно было разбито штормом.
Agent adds meaningful information.
The window was broken.
Окно было разбито.
Agent unknown or unimportant.
Use by for agents and with for instruments, and omit the agent only when doing so is appropriate.
Common mistakes include using by instead of with for instruments, using subject pronouns after by, unnecessarily repeating an obvious agent, and omitting an important agent that changes the meaning of the sentence.
The window was broken by a hammer.
Окно было разбито молотком.
Incorrect: use "with" for instruments, not "by".
The letter was sent by he.
Письмо было отправлено им.
Incorrect: use object pronoun "him" after by.
The building was designed by by a famous architect.
Здание было спроектировано известным архитектором.
Incorrect: double "by"; use one.