Who and whom both refer to people, but they differ by grammatical role. Use who for the subject of a verb, and use whom for the object of a verb or preposition. In everyday conversation, many speakers use who in places where strict grammar prefers whom, especially at the beginning of a question. This module shows how to choose correctly by identifying the role inside the clause, not by the position in the sentence.

The key distinction is role: a subject does the action or is the focus of the verb, while an object receives the action or completes a preposition. If the pronoun is the subject of its clause, choose who. If it functions as an object in its clause, choose whom. Always decide based on the role within the specific clause that contains the pronoun.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Use who for a subject	🧩 在主语处使用 who	Who called you last night?	✅ 谁昨天打电话给你？
Use whom for a direct object	🧩 在直接宾语处使用 whom	Whom did you call last night?	✅ Whom did you call last night?
Use whom after a preposition	🧩 在介词后使用 whom	To whom should I address the email?	✅ To whom should I address the email?
Decide using the role inside the clause, not sentence position	🧩 根据子句中的角色来决定，而非句子位置	Whom do you think they invited?	✅ Whom do you think they invited?

In questions, who or whom often appears at the beginning, even when it is not the subject. To choose correctly, mentally place the pronoun back into a normal statement order and see its role. If the pronoun would be he or she, use who; if it would be him or her, use whom. This is a role check, not a formality rule.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
If the answer is he or she, use who	🧩 如果答案是 he 或 she，使用 who	Who is at the door? He is at the door.	✅ Who is at the door? He is at the door.
If the answer is him or her, use whom	🧩 如果答案是 him 或 her，使用 whom	Whom did you see? I saw him.	✅ Whom did you see? I saw him.
If a preposition is fronted, whom is standard	🧩 若前置介词，whom 是标准	With whom are you meeting?	✅ With whom are you meeting?
In casual speech, who is common where whom is formal	🧩 在日常口语中，who 在 wh om 正式场合更常见	Who are you meeting with?	✅ Who are you meeting with?

In relative clauses, who and whom introduce additional information about a person. Choose who when the pronoun is the subject within the relative clause, and whom when it is the object within that relative clause. The main sentence role does not matter; only the role inside the relative clause matters. Formal writing keeps whom more consistently than conversation.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Use who as subject in the relative clause	🧩 在关系从句中将 who 作为主语	The person who called left a message.	✅ The person who called left a message.
Use whom as object in the relative clause	🧩 在关系从句中将 whom 作为宾语	The person whom I called was unavailable.	✅ The person whom I called was unavailable.
If there is a subject already, the pronoun is often an object	🧩 若已存在主语，代词通常是宾语	The person whom she hired starts Monday.	✅ The person whom she hired starts Monday.
In informal style, whom is often replaced by who or omitted	🧩 非正式风格中，whom 常被 who 替代或省略	The person I called was unavailable.	✅ The person I called was unavailable.

Prepositions take objects, so whom is the traditional choice after a preposition. In formal English, the preposition may appear before the pronoun, making whom sound especially expected. In everyday English, the preposition is often left at the end, and many speakers then use who instead of whom. Both patterns exist; the more formal the sentence, the more likely whom appears.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
After a preposition, use whom	🧩 介词后使用 whom	For whom is this package?	✅ For whom is this package?
Fronted preposition plus whom is formal	🧩 前置介词加 whom 是正式	From whom did you hear the news?	✅ From whom did you hear the news?
Stranded preposition is common in speech	🧩 介词留在末尾在口语中常见	Who did you hear it from?	✅ Who did you hear it from?
If you keep the preposition, whom sounds natural	🧩 若保留介词，whom 听起来自然	The colleague to whom I spoke agreed.	✅ The colleague to whom I spoke agreed.

When who or whom appears before phrases like do you think, did she say, or is he sure, it often belongs to a later clause. Identify the verb that the pronoun actually relates to, then decide subject or object in that clause. A common pattern is whom as the object of the embedded verb, even though the pronoun starts the full question. This is why role checking inside the embedded clause is essential.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Choose based on the embedded clause role	🧩 根据嵌入子句的角色来决定	Whom do you think they chose? They chose him.	✅ Whom do you think they chose? They chose him.
If it is the embedded subject, use who	🧩 如果它是嵌入子句的主语，使用 who	Who do you think will win? He will win.	✅ Who do you think will win? He will win.
The main verb think does not determine who vs whom	🧩 主句的 think 不决定 who vs whom	Whom did she say you invited?	✅ Whom did she say you invited?
Replace with he or him inside the embedded clause to test	🧩 用在嵌入子句中的替换测试来验证	Whom do you believe she trusted? She trusted him.	✅ Whom do you believe she trusted? She trusted him.

Modern English treats whom as more formal and more common in writing than in speech. In conversation, who often replaces whom except when preceded by a preposition like to whom or for whom, which still sounds distinctly formal. In professional writing, academic writing, and carefully edited text, whom is used more consistently for objects. Choosing who in place of whom is rarely confusing, but it changes the tone.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Whom increases formality	🧩 使用 whom 增加正式度	Whom should I contact regarding billing?	✅ Whom should I contact regarding billing?
Who is normal in casual questions	🧩 非正式问题中，who 常用	Who should I contact about billing?	✅ Who should I contact about billing?
Preposition plus whom is strongly formal	🧩 介词加 whom 在正式场合强烈正式	To whom it may concern	✅ To whom it may concern
In very informal style, you can avoid both with rephrasing	🧩 非正式风格中可通过改写避免两者	Who should I reach out to about billing?	✅ Who should I reach out to about billing?

Some sentence shapes appear frequently and make the choice predictable once you know the role. If the pronoun is followed by a verb directly, it is often the subject and uses who. If it is followed by a subject plus verb, it is often the object and may use whom. Recognizing these patterns speeds up decisions, especially in writing.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Who plus verb often signals subject	🧩 Who 加动词通常表示主语	Who wrote this report?	✅ Who wrote this report?
Whom plus subject plus verb often signals object	🧩 Whom 加 主语 加 动词常表示宾语	Whom did you hire?	✅ Whom did you hire?
Whom plus noun subject is common in formal questions	🧩 Whom 加 名词主语在正式问题中常见	Whom should we invite?	✅ Whom should we invite?
After verbs like meet, call, hire, choose, the pronoun is often an object	🧩 在 meet、call、hire、choose 等动词后，代词常作宾语	Whom did they meet yesterday?	✅ Whom did they meet yesterday?

To choose between who and whom reliably, isolate the clause that contains the missing role and supply a temporary pronoun. If you would say he or she in that spot, use who; if you would say him or her, use whom. If there is a preposition directly linked to the pronoun, whom is the traditional object form. If the sentence feels too formal with whom, you can often rewrite to keep who without sounding incorrect in modern usage.

Rule	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Replace with he or she to confirm who	🧩 用 he 或 she 进行替换以确认 who	Who is responsible? She is responsible.	✅ Who is responsible? She is responsible.
Replace with him or her to confirm whom	🧩 用 him 或 her 进行替换以确认 whom	Whom are you emailing? I am emailing him.	✅ Whom are you emailing? I am emailing him.
If a preposition governs it, prefer whom in formal style	🧩 若有介词支配，正式风格偏好 whom	With whom did you speak?	✅ With whom did you speak?
Rewrite to avoid whom while staying clear	🧩 通过改写避免 whom 同时保持清晰	Who did you speak with?	✅ Who did you speak with?

Who is the subject form and whom is the object form, including after prepositions. The correct choice depends on the role within the relevant clause, which is especially important in questions and embedded clauses. Whom is more common in formal writing, while who is widely used in casual speech even where strict grammar prefers whom. With clause role checks and the he or him test, you can choose confidently and control the tone of your English.