Grammar Rule in 30 Seconds
Use modal passives to focus on the action's necessity or possibility without needing to mention who is performing it.
- Present/Future: Use 'Modal + be + Past Participle' (e.g., 'It must be finished').
- Past: Use 'Modal + have been + Past Participle' (e.g., 'It should have been done').
- Negative: Place 'not' after the modal (e.g., 'It cannot be changed').
Overview
The report must be submitted by Friday（报告必须在周五前提交）会强调报告的状态和截止日期，而不是说Someone must submit the report by Friday（某人必须在周五前提交报告），后者将焦点放在了一个未指明的个人身上。这种语法选择体现了语言在强调主体和焦点方面的灵活性，使说话者能够根据沟通意图来调整句子的侧重点。熟练运用此结构，能显著提升你理解和运用高级英语的能力。be的动词原形（base form）以及主要动词的过去分词（past participle）结合起来运作的。其核心原理是：情态动词本身形式不随主语变化（例如，can对I、you、he都一样），并且后面必须跟动词原形。在被动语态中，这个动词原形永远是be，而不是is、are、was或were。be保持非时态、非屈折（untensed and uninflected）的状态，因为情态动词已经携带了时态和语气信息。例如，在The work can be finished（工作可以完成）中，can表达了可能性，而be是连接过去分词finished的必要环节。过去分词（规则动词加-ed，不规则动词用第三种形式，如do的过去分词是done）一致地表示主语所经历的、已完成的动作。一旦掌握了这个基本模式，其构成就会变得相当简单。Someone should write the proposal（某人应该写这份提案）将写作动作归因于一个未指明的someone。转换为被动语态后，The proposal should be written（这份提案应该被写出来），焦点完全转移到了proposal（提案）和它被创作的必要性上。原先的主动者（someone）要么被省略，要么如果很重要，可以通过by短语来引入，例如The proposal should be written by the end of the week（这份提案应该在一周结束前写完）。It is possible for people to solve this problem（人们有可能解决这个问题），不如简洁地说This problem can be solved（这个问题可以被解决）。被动语态本质上使动作非人称化，使其适用于科学写作、政策声明或任何结果比执行者更重要的语境。be+过去分词的固定结构不同。英文的这种结构在表达“可能性”、“义务”等情态时，直接将焦点放在承受者身上，是一种非常精炼的表达方式。主语 (Subject) + 情态动词 (Modal Verb) + be + 过去分词 (Past Participle / V3)can, could, may, might, must, should, will, would）表达确定性、义务或可能性的程度。关键在于，be 总是跟在情态动词后面，并且是它的原形。它不会根据人称或单复数发生变化。最后，过去分词（也称为V3）是主要动词的第三种形式，通常跟在have后面构成完成时态（例如，written, taken, given）。not放在情态动词之后形成的：主语 (Subject) + 情态动词 (Modal Verb) + not + be + 过去分词 (Past Participle / V3)The application cannot be processed without all documents.（没有所有文件，申请无法被处理。）This information should not be shared externally.（这些信息不应被对外分享。）
情态动词 (Modal Verb) + 主语 (Subject) + be + 过去分词 (Past Participle / V3)?Can the changes be implemented by next week?（这些变更能在下周被实施吗？）Should the new policy be announced tomorrow?（新政策应该明天被宣布吗？）
must not be done | “不必须被做” (不常用，不如“不能做”或“不能这样”) |should not be shared | “不应该被分享” |cannot be processed | “不能被处理” |Can the changes be implemented? | “这些变更能被实施吗？” |Should the new policy be announced? | “新政策应该被宣布吗？” |not直接放在情态动词后，疑问句则将情态动词提到句首，结构非常固定。而中文的否定和疑问标记则更加灵活，有时甚至依赖语调。- 1当施动者未知或不重要时： 这是最常见的原因。如果你不知道谁执行了某个动作，或者识别出他们并不重要，被动语态允许你讨论动作本身。
The website must be updated regularly.（网站必须定期更新。）（我们知道是“某人”更新，但焦点在于网站“需要”更新这件事。）My keys could be left in the office.（我的钥匙可能被落在办公室了。）（说话者不知道是谁落下的，或者是否是故意留下的。）
- 1为了强调动作或其承受者： 通过将动作的承受者置于主语位置，你可以突出发生在他们身上的事情，而不是谁引起了这件事。
The new regulations will be enforced starting next month.（新规定将从下个月开始执行。）（强调“执行”这个动作，而非执行机构。）Serious errors could be avoided with better planning.（通过更好的规划可以避免严重的错误。）（焦点在于“避免错误”的可能性。）
- 1用于正式和客观的语境，尤其是在学术或专业场合： 被动语态本身就能营造一种更客观、更非人称的语气，这在报告、科学论文或官方公告中通常是首选。它避免了个人偏见，专注于事实和流程。
All samples should be stored at constant temperature.（所有样本都应储存在恒定温度下。）（科学指导，强调“储存”这个过程。）Proposals may be submitted via the online portal.（提案可以通过在线门户提交。）（正式指示，避免直接命令“你”。）
- 1用于礼貌地给出指示、规则或建议： 在给出指令时，被动语态可以软化命令的语气，使其听起来更像是一个普遍程序或建议，而不是直接的命令。
Safety guidelines must be followed at all times.（安全指南必须始终被遵守。）（这是一个规则，而不是直接说You must follow safety guidelines。）Further research might be conducted to confirm these findings.（可能需要进行进一步的研究来证实这些发现。）（对未来行动的建议。）
- 1讨论可能性、概率或假设情况时： 情态动词本身就与可能性或条件性有关。当它们与被动语态结合时，它们描述了某事物可能、能够或应该发生什么。
A new vaccine might be developed within the next year.（一种新疫苗可能在明年内被研发出来。）（表达关于疫苗的未来可能性。）If approved, the project would be launched in Q3.（如果获批，该项目将在第三季度启动。）（假设的未来结果。）
- 英文：
Safety guidelines must be followed at all times. - 中文：
安全指南必须遵守。（这是最接近的翻译，但中文的“遵守”可以理解为主动行为，语境使其偏向被动含义。） - 或者更自然的中文：“大家要遵守安全指南。”（这里“大家”是主语，但语气是普遍性的指示。）
- 英文：
Proposals may be submitted via the online portal. - 中文：
提案可以通过在线门户提交。（这里“提交”可以看作是动作，但“提案”是逻辑主语，可以被提交。） - 或者更自然的中文：“您可以通过在线门户提交提案。”（直接面向接收者。）
- 1在情态动词后省略
be： 这可以说是最普遍的错误。情态动词总是需要紧跟一个动词原形。在被动语态中，这个动词原形永远是be。
- 错误：
The document must signed before submission. - 正确：
The document must be signed before submission.（文件必须在提交前被签署。） - 为什么错误： 没有
be，signed就变成了过去分词作形容词，而不是构成被动动词短语的一部分。情态动词需要一个纯粹的动词原形来完成其结构，而be充当了这个角色。
- 1使用
be的屈折形式（如is,are,was,were）代替be： 情态动词不允许其后的动词屈折变化。be必须保持其原形。
- 错误：
The report can is finished by Friday. - 正确：
The report can be finished by Friday.（报告可以在周五前完成。） - 为什么错误： 情态动词已经携带了时态/语气信息；其后的动词（
be）必须是未时态、未屈折的原形。像is这样的屈折形式只用于被动语态的其他时态中（例如，The report is finished）。
- 1使用主要动词的原形或不定式代替过去分词： 被动语态的本质要求使用过去分词（V3）来表达主语所承受的、已完成的动作。
- 错误：
The decision should be make soon. - 正确：
The decision should be made soon.（这个决定应该很快被做出。） - 为什么错误： 原形动词
make（V1）是主动的。被动结构依赖于过去分词made（V3）来表示主语经历了该动作。这里的英语动词形式至关重要。
- 1错误选择情态动词以致含义不清： 即使语法正确，选择错误的情态动词也会严重改变句子的意思，导致C1级别的沟通失误。
- 如果你想表达强烈的必要性：
The task must be completed by noon.（任务必须在中午前完成。） - 如果你说：
The task might be completed by noon.，这只传达了很小的可能性，可能不是你对截止日期的本意。 - 为什么错误： 每个情态动词都带有关于确定性、义务或许可的不同含义。混淆
should（建议）与must（强迫）或might（弱可能性）与can（一般能力）会改变整个信息。务必将情态动词与你想要表达的精确细微差别对齐。
- 1过度使用被动语态： 虽然有效，但频繁使用被动语态会使写作听起来过于正式、晦涩或闪烁其词。主动语态通常更直接、更吸引人。
- 考虑：
The team will implement the new strategy.（团队将实施新策略。）（直接，施动者清晰。） - 对比：
The new strategy will be implemented by the team.（新策略将由团队实施。）（仍然可以接受，但如果施动者不重要，有时会显得不那么直接。）
- “被”字句的思维定势： 中文使用者习惯于使用“被”来标记被动，或者通过语序来体现。在学习英文被动语态时，要警惕将“被”的概念直接套入。英文被动语态的构成（
be + V3）是核心，而不是某个特定的标记词。 - 情态动词的直接性： 中文的情态动词（能、可以、应该、必须）后面通常直接跟动词。例如，“我能去”、“他必须吃”。而在英文情态被动中，必须插入
be。很多学生会漏掉be，直接说must go（这是主动）而不是must be gone（被动，虽然这个例子不太常用，但结构是这样的）。 - 主动与被动的选择： 中文在很多情况下可以用主动句表达被动含义（如“这个问题他解决了”），而英文则更倾向于在需要时使用明确的被动结构。因此，在翻译或写作时，要根据英文的习惯来判断何时使用被动语态，而不是仅仅依赖中文的表达习惯。
be的相应时态（is/am/are/was/were/been/being）加上过去分词。而情态被动语态则是在情态动词后固定使用be + 过去分词。Subject + be (tensed) + Past Participle | Subject + Modal Verb + be (base form) + Past Participle |be动词的时态决定（现在时、过去时等） | 由情态动词决定（表示可能性、义务、能力等） |The letter was written yesterday. | The letter should be written by tomorrow. |Subject (Agent) + Verb + Object (Recipient) | Subject (Recipient) + Modal + be + Past Participle |Someone can fix the car. | The car can be fixed. |You must complete the task. (你必须完成任务。) | The task must be completed. (任务必须被完成。) |It must done？be。所以正确的形式是It must be done。It must done在语法上是错误的，因为它缺少了连接情态动词和过去分词的必要桥梁be。Can, could, may, might, must, should, will, would 这些情态动词后面都可以接be + 过去分词吗？be + 过去分词的模式，只是表达的含义不同。例如：This can be done（可能性），This must be done（义务），This might be done（弱可能性），This should be done（建议/期望）。is done, was done）。例如：The door is locked.（门被锁了——描述状态）vs. The door must be locked.（门必须被锁——表达义务）。by短语来引入执行者（施动者）。例如：The report should be finished by the marketing team.（这份报告应该由市场部来完成。）或者This task can be completed by anyone with basic training.（这项任务可以由任何有基本培训的人来完成。）Modal Passive Formation
| Timeframe | Modal | Auxiliary | Verb Form | Example |
|---|---|---|---|---|
|
Present/Future
|
can/must/should
|
be
|
Past Participle (V3)
|
It can be done.
|
|
Past
|
could/should/must
|
have been
|
Past Participle (V3)
|
It should have been done.
|
|
Negative (Pres)
|
cannot/must not
|
be
|
Past Participle (V3)
|
It must not be done.
|
|
Negative (Past)
|
might not
|
have been
|
Past Participle (V3)
|
It might not have been done.
|
|
Question
|
Should
|
Subject + be
|
Past Participle (V3)
|
Should it be done?
|
Common Contractions
| Full Form | Contracted Form | Usage Note |
|---|---|---|
|
cannot be
|
can't be
|
Very common in speech
|
|
should not be
|
shouldn't be
|
Common in advice
|
|
must not be
|
mustn't be
|
Common in British English
|
|
should have been
|
should've been
|
Spoken English only
|
Meanings
The modal passive is used to express necessity, possibility, permission, or obligation regarding an action where the receiver of the action is the subject.
Obligation and Necessity
Expressing that an action is required to be performed on an object.
“Safety goggles must be worn at all times in the lab.”
“The taxes should be paid by the end of the month.”
Possibility and Ability
Expressing what can or could happen to an object.
“The problem could be solved with more funding.”
“This software can be downloaded for free.”
Past Regret or Deduction
Reflecting on actions that were or weren't performed in the past.
“The mistake should have been caught during the review.”
“The package must have been delivered to the wrong address.”
Reference Table
| 情态动词 (Modal) | 含义 | 主动示例 | 被动示例 |
|---|---|---|---|
|
can
|
能力/可能性
|
They can solve the problem.
|
The problem can be solved.
|
|
could
|
可能性/建议
|
We could reschedule the meeting.
|
The meeting could be rescheduled.
|
|
may
|
许可/可能性
|
You may use this tool.
|
This tool may be used.
|
|
might
|
微弱可能性
|
She might send the email.
|
The email might be sent.
|
|
must
|
义务/必要性
|
Students must read the book.
|
The book must be read.
|
|
should
|
建议/推荐
|
You should review the report.
|
The report should be reviewed.
|
|
will
|
未来确定性
|
They will complete the task.
|
The task will be completed.
|
|
would
|
假设结果
|
Someone would enjoy this.
|
This would be enjoyed.
|
正式程度
The report must be finalized by the close of business. (Workplace deadline)
The report should be finished soon. (Workplace deadline)
The report's gotta be done. (Workplace deadline)
This doc needs to be wrapped up ASAP. (Workplace deadline)
情态动词被动语态：核心概念
关键要素
- 情态动词 Can, Should, Must, etc.
- be 始终用 'be'
- 过去分词 V3 形式
主要目的
- 关注动作 而非执行者
- 执行者未知 或不重要
- 礼貌得体 间接的请求/建议
使用语境
- 指令 规则、程序
- 可能性 未来的结果
- 建议 推荐
主动语态 vs. 情态动词被动语态
我该使用情态动词被动语态吗？
动作的执行者是否未知或不重要？
你需要表达可能性、必要性或建议吗？
你想听起来更正式或更客观吗？
被动语态中的情态动词含义
义务
- • Must be done
- • Has to be done
可能性
- • Can be done
- • Could be done
- • May be done
- • Might be done
建议
- • Should be done
- • Ought to be done
将来
- • Will be done
按水平分级的例句
The car can be washed.
El coche se puede lavar.
The food must be eaten.
La comida debe ser comida.
The door should be closed.
La puerta debería estar cerrada.
Can the window be opened?
¿Se puede abrir la ventana?
The bill must be paid now.
La cuenta debe pagarse ahora.
The letters can be sent tomorrow.
Las cartas pueden enviarse mañana.
The room should be cleaned every day.
La habitación debe limpiarse todos los días.
This game cannot be played alone.
Este juego no se puede jugar solo.
The results might be announced later today.
Los resultados podrían anunciarse más tarde hoy.
All staff members must be informed of the change.
Todos los miembros del personal deben ser informados del cambio.
The bridge could be built in two years.
El puente podría construirse en dos años.
Should the meeting be rescheduled?
¿Debería reprogramarse la reunión?
The report should have been submitted yesterday.
El informe debería haber sido entregado ayer.
The software may be updated automatically.
El software puede actualizarse automáticamente.
The suspect must have been seen by someone.
El sospechoso debe haber sido visto por alguien.
These rules ought to be followed strictly.
Estas reglas deberían seguirse estrictamente.
The proposal could have been more clearly articulated.
La propuesta podría haber sido articulada más claramente.
It must be ensured that all safety protocols are met.
Debe asegurarse de que se cumplan todos los protocolos de seguridad.
The data might have been misinterpreted by the researchers.
Los datos podrían haber sido malinterpretados por los investigadores.
Such behavior will not be tolerated in this institution.
Tal comportamiento no será tolerado en esta institución.
The nuances of the contract ought to have been more thoroughly scrutinized.
Los matices del contrato deberían haber sido escrutados más a fondo.
The artifacts may well have been being moved when the fire broke out.
Es muy posible que los artefactos estuvieran siendo trasladados cuando estalló el incendio.
It shall be deemed that the agreement is null and void.
Se considerará que el acuerdo es nulo y sin valor.
The project could not have been brought to fruition without your support.
El proyecto no podría haber llegado a buen término sin su apoyo.
容易混淆
Learners often use the active form when they mean the passive, especially with 'should have'.
Mixing up the perfect active and perfect passive.
Using 'must not' for logical impossibility.
常见错误
It must done.
It must be done.
The car can washed.
The car can be washed.
It can be do.
It can be done.
Must be it done?
Must it be done?
It should be finish.
It should be finished.
The bill must be pay.
The bill must be paid.
It not can be done.
It cannot be done.
It should have done.
It should have been done.
The work might been finished.
The work might have been finished.
It must be being done.
It must be done.
The data should have been being analyzed.
The data should have been analyzed.
It ought to been seen.
It ought to have been seen.
The results can be interpreted as...
The results could be interpreted as...
It must not have been done.
It can't have been done.
句型
The ___ must be ___ by ___.
It could be argued that ___.
The ___ should have been ___ earlier.
Under no circumstances may the ___ be ___.
Real World Usage
The files should be uploaded to the shared folder by EOD.
The deposit shall be returned within 30 days.
The bracket must be secured with four screws.
The results could be interpreted as a shift in consumer behavior.
Baggage must not be left unattended.
Your password can be reset using the link below.
永远记得带上 'be'
It must be done correctly.
盯紧你的 V3 形式！
The message should be sent immediately.
少用 'by' 引导执行者
The bug can be fixed without help.
语境决定一切
The results might be influenced by temperature.
副词的灵活位置
The rules can be easily changed.
Smart Tips
Change 'I must finish this' to 'This must be finished'. It sounds less like a personal struggle and more like a professional requirement.
Use 'should have been' to focus on the task. It reduces conflict.
Check if there is a modal before it. If so, it's a modal passive!
Use 'could be interpreted' or 'might be seen' to avoid sounding too aggressive with your claims.
发音
Reduction of 'be'
In the phrase 'must be done', the word 'be' is often unstressed and shortened.
Contraction of 'have been'
In 'should have been', 'have been' often sounds like 'av-bin' or 'əv bɪn'.
Stress on the Modal
It MUST be done! (Falling arrow on MUST)
Emphasizing the urgency or necessity.
记住它
记忆技巧
Remember 'MBP': Modal + Be + Participle. It's the 'Most Basic Passive' for modals!
视觉联想
Imagine a robot (the object) being repaired. The robot doesn't fix itself; it 'must be fixed' by a factory arm. The focus is on the robot, not the arm.
Rhyme
If a modal is what you see, don't forget to add the 'be'!
Story
A detective arrives at a crime scene. He says, 'The safe must have been opened from the inside. The guards should have been alerted.' He focuses on the objects and actions because the criminal is unknown.
Word Web
挑战
Look around your room. Find 3 things that 'should be cleaned' and 2 things that 'could be moved'. Say them out loud.
文化笔记
British speakers use 'mustn't be' more frequently than Americans, who prefer 'can't be' or 'shouldn't be' for prohibitions.
Modal passives are the standard for 'polite distancing'. It allows a manager to criticize a process without criticizing a person.
The modal 'shall' is almost exclusively used in legal passives to indicate a mandatory requirement.
The passive voice in English evolved from Old English 'weorthan' (to become) and 'beon' (to be). Modals were originally full verbs with their own meanings.
对话开场白
What is one thing in your city that should be improved?
Think of a famous historical event. What should have been done differently?
If you were the president, what laws would be changed immediately?
Can a person's character be judged by their clothes?
日记主题
常见错误
Test Yourself
The new rules ___ reviewed by the committee soon.
Find and fix the mistake:
The report should be write by tomorrow morning.
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
Score: /3
练习题
8 exercisesThe report ___ (must / finish) by tomorrow morning.
Find and fix the mistake:
The car should been fixed yesterday.
Which sentence is most objective?
The stars...
In a modal passive, the word 'be' changes to 'am/is/are' depending on the subject.
A: Why is the office so messy? B: I don't know, it ___ (should / clean) last night.
Select the correct form.
Must be done / Could be done / Should have been done
Score: /8
Practice Bank
13 exercisesThe payment ___ processed by the end of the week.
Her application could be approve soon.
选择正确的句子：
将这句话翻译成英语：'这个问题可以被解决。'
将这些单词排列成句子：
将主动语态句子与其正确的被动语态对应项匹配：
This sensitive information ___ not be shared outside the company.
A decision will being made by next week.
哪个句子是正确的？
将这句话翻译成英语：'这可以在会议上讨论。'
重新排列这些单词：
Your reservation ___ be confirmed shortly via email.
将情态动词与其隐含的语境匹配：
Score: /13
常见问题 (8)
Yes, in informal English. For example, 'It needs to get done' instead of 'It needs to be done'. However, 'be' is much more common in writing.
'Must not be' is for rules (prohibition), while 'cannot be' is for things that are impossible.
Use the word `by` at the end. 'The law must be signed `by the President`.'
Yes, they are almost identical in meaning, but 'ought to' is slightly more formal or moralistic.
Technically yes (modal passive continuous), but it is very rare and usually replaced by simpler forms like 'might be happening'.
To sound objective. Scientists care about the experiment, not the person holding the test tube. 'The liquid must be heated' sounds more scientific than 'I must heat the liquid'.
No, you are missing the word `have`. It must be 'It should `have` been done'.
When the 'doer' of the action is the most important part of the sentence or when you want to be very direct and personal.
Scaffolded Practice
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2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Pasiva con estar/ser o Pasiva Refleja
English uses 'be' + V3, while Spanish often uses 'se' + active verb.
Voix passive avec les modaux
French uses 'on' more frequently than English uses the passive.
Passiv mit Modalverben
German puts the past participle and 'werden' at the end of the sentence.
助動詞 + 受動態 (reru/rareru)
Japanese uses verb suffixes rather than auxiliary verbs like 'be'.
المبني للمجهول مع الأفعال الناقصة
Arabic uses internal vowel changes (morphology) rather than a 'be' auxiliary.
被 (bèi) + Modal
Chinese lacks verb conjugation and the 'be' auxiliary for passives.
Learning Path
Prerequisites
Learn These First
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