Agent Phrases with Bởi and Do

Vietnamese can identify the performer or cause of an event with bởi and do, especially in news, academic prose, official notices, and other formal writing. These words sometimes correspond to English by, but they are not interchangeable passive markers. Bởi + noun phrase can add an agent or cause after an affected-subject construction; do + noun phrase + predicate often builds a compact “created/performed by...” modifier or introduces a cause.

Everyday Vietnamese frequently prefers an active clause, an agent directly after bị/được, or no agent at all. Choosing bởi/do is therefore a question of information structure and register, not a compulsory step in translating an English passive. This page leaves the broader strategy of putting an affected object first without passive morphology to Object Promotion without Passive Morphology.

A practical map

In the first sentence, một nhóm kỹ sư trẻ is an intentional agent. In the second, do sinh viên Việt Nam phát triển modifies ứng dụng and packages its creator compactly. In the third, thời tiết xấu is a cause, not an agent intentionally doing the canceling.

Bởi with agents: possible, formal, and often avoidable

The pattern affected participant + bị/được + predicate + bởi + agent closely resembles an English passive with by. It is grammatical and useful when a formal text must keep the affected participant as topic while also naming the agent.

In conversation, however, the corresponding active clauses are usually lighter and more natural: Hội đồng chuyên môn đã phê duyệt báo cáo này; Một nhóm vũ trang kiểm soát khu vực này. A direct agent slot is also possible with many affected-subject constructions: Tôi được cô giáo khen, Tôi bị cảnh sát phạt.

English speakers tend to overproduce bởi because English requires a preposition before a postverbal agent. Vietnamese does not. Use bởi when the formal discourse structure genuinely calls for it, not merely because the English source says by. Judgments are especially conservative with human agents: many editors prefer được + agent + predicate, a do modifier, or an active clause and regard postposed bởi + person as translation-influenced.

Do with creators and responsible actors

The compact pattern noun + do + agent + predicate is extremely useful in descriptions, credits, labels, and formal prose. The whole do... sequence modifies the noun.

The agent comes between do and the unchanged predicate: do chị Mai viết, not an English-style finite relative clause. In everyday speech, a relative construction without do may be more direct: cuốn sách chị Mai viết “the book Mai wrote.” Do signals an explicit producer-responsibility relationship and helps readers parse a dense noun phrase.

Do for causes; bởi and bởi vì for reasons

Do + noun phrase commonly introduces the cause of an event in reports and notices. It answers “what caused this?” rather than “who performed this action?”

Initial do + clause is a formal causal adjunct. In ordinary conversation, vì is usually more natural: Vì hệ thống bị lỗi nên tôi không đăng nhập được “Because the system has an error, I can't log in.” Bởi vì also means “because” and can occur in speech or writing, but that conjunction is a unit; it should not be confused with a post-event bởi + agent phrase.

The event predicate still does not conjugate

Adding bởi or do never changes the predicate form. Time and viewpoint are expressed separately.

The first sentence uses the more idiomatic direct agent position được chính phủ phê duyệt. The second retains bởi because a formal project description keeps the project topical and supplies a long agent phrase. Phê duyệt and thực hiện remain unchanged; đã and sẽ contribute viewpoint and future orientation.

Six baseline predicate types

Not every predicate licenses an agent phrase. The performer/cause distinction must make semantic sense.

In the first, do mẹ tôi nấu modifies bữa cơm; làm then introduces the result ai cũng nhớ nhà. In the second, human actors follow do inside concise attribution structures. Cô ấy là giáo viên still requires là for classification, while Trời lạnh takes no copula. Neither construction becomes passive merely by adding an English-looking preposition.

Choosing among four natural organizations

Suppose a committee approved a plan. Vietnamese can organize the same event differently:

No one form is a mechanical translation of English passive voice. The active version is often best. The direct được + agent + predicate pattern keeps the plan topical without a heavy postposed phrase. Bởi is available for formal balance or a long agent. Do makes an attributive unit that generally needs a larger sentence.

In context

The first do introduces a non-agentive cause. Do nhà ga gửi attributes the notice to its sender. Bởi đội kỹ thuật names an intentional agent in a formal reported message. Final and post-predicate được concern feasibility, not agent marking.

Quick decision aid

1. Is a normal active clause clear and natural? Prefer it.
2. Must the affected participant remain topic while a formal text names the actor? ... bởi + agent is available.
3. Does a noun need a compact creator/performer modifier? Use noun + do + agent + predicate.
4. Are you explaining why an event happened? Use causal do + noun/clause, especially in writing; vì is more conversational.
5. Is the agent short and naturally placed after bị/được? A direct agent slot often beats bởi.
6. Does the predicate denote a state, identity, possession, or existence with no performer? Do not invent an agent phrase.
7. Is English by expressing a means—by bus, by hand, by chance—rather than an agent? Translate the actual relation, not the word by.

Common Mistakes

1. Adding bởi to every English passive.

The direct agent position is the normal colloquial choice.

2. Using causal do when the intended relation is simply an acting agent.

Use an active clause when the actor is the main information. By contrast, Chuyến bay bị hủy do sương mù dày đặc naturally gives dense fog as the cause. Formal causal bởi is also possible, so a bởi phrase should not automatically be labeled an intentional agent.

3. Copying English word order into a do modifier.

The pattern is do + agent + predicate.

4. Inserting là before a property predicate.

Là marks appropriate nominal classification, not every English be.

5. Translating every English by as bởi.

Means or instrument uses bằng; bởi introduces an agent or cause in the relevant formal structures.

Key Takeaways

Bởi and do are useful but register-sensitive. Post-event bởi + agent is mainly formal; do + agent + predicate efficiently attributes a noun to its creator or performer; causal do introduces a reason. None of these creates verb agreement or tense. Prefer active clauses and direct bị/được + agent + predicate patterns when they are more natural, and never force a formal by phrase onto identities, properties, possession, or existence.