上級英語法助動詞

可能性と推論

"must have done"

Strong logical deduction about a past event (near certainty)

"She must have left early — her coat is gone and the lights are off."

可能性と推論

"can't have done"

Logical impossibility about a past event

"He can't have finished the report already; he only started an hour ago."

可能性と推論

"could have done"

Past possibility that did not necessarily happen

"The package could have been delivered while we were out."

可能性と推論

"might have done"

Weak possibility about a past event

"I might have left my keys at the office — I'm not sure."

可能性と推論

"should have arrived"

Expected outcome based on probability (past expectation)

"The train should have arrived by now; something must be wrong."

可能性と推論

"ought to have done"

Expectation or obligation not fulfilled (formal register)

"The results ought to have been verified before the announcement was made."

可能性と推論

"may well"

Fairly strong possibility in the present or future

"The negotiations may well collapse if neither side compromises."

可能性と推論

"could well"

Reasonable probability, slightly less formal than "may well"

"This development could well change the entire course of the project."

義務と必要性

"need not have done"

An action was performed but it was unnecessary

"You need not have printed all those copies — we went digital in the end."

義務と必要性

"didn't need to"

An action was not necessary (and may not have been done)

"I didn't need to attend the entire conference, just the morning session."

義務と必要性

"had to have done"

Strong deduction that a past obligation was fulfilled

"She had to have known about the policy — it was distributed company-wide."

義務と必要性

"must not"

Strong prohibition; forbidden

"Candidates must not bring electronic devices into the examination hall."

義務と必要性

"be supposed to"

An expected obligation based on rules or prior arrangement

"The contractor is supposed to deliver the final build by Friday."

義務と必要性

"had better"

Strong advice with implied negative consequence

"You had better review the contract before signing — there are unusual clauses."

義務と必要性

"be bound to"

Something is certain to happen due to a strong tendency

"With that workload, burnout is bound to occur unless the team expands."

義務と必要性

"be required to"

Formal obligation imposed by authority, rules, or law

"All directors are required to declare any conflicts of interest at the annual meeting."

能力と可能性

"was able to"

Successfully managed to do something on a specific occasion (not "could")

"Despite the delays, the team was able to deliver the project on schedule."

能力と可能性

"could not have done"

It was impossible to have done something (past ability limitation)

"Without your assistance, I could not have completed the analysis in time."

能力と可能性

"managed to"

Succeeded in doing something difficult

"The negotiators managed to reach a preliminary agreement after three days of talks."

能力と可能性

"could have done but didn't"

Had the ability but chose not to use it

"She could have taken a more senior role but preferred to remain in research."

能力と可能性

"be capable of"

Has the inherent ability or potential to do something

"The new algorithm is capable of processing one million queries per second."

能力と可能性

"can't help but"

Unable to prevent oneself from doing or feeling something

"You can't help but admire the precision of the engineering."

能力と可能性

"couldn't have been more"

Expresses that something has reached the maximum degree possible

"The timing couldn't have been more fortuitous for the merger announcement."

能力と可能性

"would be able to"

Conditional ability — given the right circumstances

"With an extended budget, the research team would be able to run a longitudinal study."

許可と形式性

"might I ask"

Extremely polite and formal way to introduce a question

"Might I ask what the timeline is for the final decision on the proposal?"

許可と形式性

"would you mind"

Polite request; expects agreement but gives the other person choice

"Would you mind reviewing the draft before the board meeting tomorrow?"

許可と形式性

"I wonder if you could"

Very soft, indirect request in formal or professional settings

"I wonder if you could clarify the methodology section of the report."

許可と形式性

"may I be permitted to"

Highly formal request for permission, often in written or official contexts

"May I be permitted to address the panel on the matter of data integrity?"

許可と形式性

"you are welcome to"

Granting permission warmly or generously

"You are welcome to use our facilities for the duration of the residency."

許可と形式性

"feel free to"

Informal permission; encourages the other person to act without hesitation

"Feel free to reach out if any further questions arise during the review."

許可と形式性

"should you wish to"

Formal conditional phrasing for offering an option

"Should you wish to appeal the decision, you must do so within fourteen days."

許可と形式性

"I'm afraid that's not possible"

Polite refusal, often used in professional or customer-facing contexts

"I'm afraid that's not possible under the current data-sharing agreement."

条件文の法助動詞

"should you choose to"

Formal inverted conditional without "if" (first conditional)

"Should you choose to withdraw your application, please notify us in writing."

条件文の法助動詞

"were it not for"

Formal inverted second conditional expressing a counterfactual

"Were it not for the team's commitment, the deadline could not have been met."

条件文の法助動詞

"had it not been for"

Third conditional counterfactual in formal inverted structure

"Had it not been for the early warning, the data breach would have gone undetected."

条件文の法助動詞

"would have thought"

Surprise or counterintuitive reflection on a past expectation

"Who would have thought the simpler design would outperform the complex prototype?"

条件文の法助動詞

"could have been avoided"

Expresses that a negative past event was preventable

"The misunderstanding could have been avoided with clearer communication from the outset."

条件文の法助動詞

"might otherwise have"

Contrasts what happened with a hypothetical alternative outcome

"The company might otherwise have missed the regulatory window entirely."

条件文の法助動詞

"should have been"

A past ideal that was not achieved — regret or criticism

"The safety protocols should have been in place before operations commenced."

条件文の法助動詞

"would sooner … than"

Expresses a strong conditional preference

"She would sooner resign than compromise the integrity of the findings."

ニュアンス・スタンス・レジスター

"will tend to"

Describes a predictable general behaviour or pattern

"Prices will tend to rise when demand consistently outstrips supply."

ニュアンス・スタンス・レジスター

"would appear to"

Tentative, distanced observation — more formal than "seems to"

"The preliminary results would appear to support the original hypothesis."

ニュアンス・スタンス・レジスター

"cannot but"

Formal equivalent of "can't help but"; expresses inevitability

"One cannot but admire the rigour with which the study was designed."

ニュアンス・スタンス・レジスター

"it would be remiss not to"

Signals an important point that would be wrong to omit

"It would be remiss not to acknowledge the limitations of this dataset."

ニュアンス・スタンス・レジスター

"dare not"

Afraid or unwilling to do something (formal or literary register)

"The committee dare not ignore the implications of the audit findings."

ニュアンス・スタンス・レジスター

"may I venture to suggest"

Extremely tentative, polite suggestion — typical of formal meetings

"May I venture to suggest that a phased rollout would reduce operational risk?"

ニュアンス・スタンス・レジスター

"will have"

Future perfect modal — certainty about what will be completed by a future point

"By the time the panel meets, the committee will have reviewed all submissions."

ニュアンス・スタンス・レジスター

"would rather not"

Polite expression of reluctance or preference to avoid something

"I would rather not speculate on the findings before the full report is released."