B2 Verb Moods 10 min read ふつう

過去の可能性：〜できたのに (Could Have)

「could have」は、過去に「possible in the past」だったけれど、「did not occur」した行動について話す時に使います。
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Grammar Rule in 30 Seconds

Use 'could have' to talk about things that were possible in the past but did not actually happen.

  • Use 'could have' + past participle for missed opportunities, like 'I could have won.'
  • Use 'couldn't have' for things that were impossible, like 'He couldn't have known.'
  • Always use 'have' (never 'of'), even though it sounds like 'of' when spoken quickly.
👤 + could + have + 🏁 (Past Participle)

Overview

### Overview
英語学習において、B1からB2レベルへとステップアップする際の最大の壁の一つが、「事実ではない過去」をいかに表現するかという点です。単に「昨日何をしたか」を述べる段階を過ぎ、上級者を目指す皆さんは、「もしあの時こうしていれば、別の結果があったかもしれない」という仮定の話や、過去の可能性について、より精密に語る能力が求められます。
今回詳しく解説する could have + 過去分詞（V3）は、まさにそのための核心的なグラマーです。これは専門用語で「法助動詞＋完了形（Modal Perfect）」と呼ばれ、「実際には起こらなかった過去の可能性」を表現するために使われます。日本語で言うところの「〜できたはずだったのに（実際はしなかった）」「〜ということもあり得た（実際はそうならなかった）」というニュアンスを完璧にカバーする表現です。
この文法をマスターすることは、単に知識を増やすこと以上の意味があります。ビジネスシーンでの反省会、友人との思い出話、あるいはニュースの分析など、現実とは異なる「ifの世界」を語ることで、あなたの英語表現に奥行きと洗練さが加わります。「事実はこうだったが、別の選択肢もあった」という複雑な思考を英語で論理的に伝えるための、非常に強力なツールになるのです。これから、その仕組みと使い方を、日本語話者の視点から徹底的に紐解いていきましょう。
### How This Grammar Works
could have + 過去分詞の構造を理解するためには、まず英語の「法助動詞（Modal verbs）」と「完了形（Perfect aspect）」が組み合わさった時の化学反応に注目する必要があります。
#### 1. 構造の分解
  • could: 元々は can の過去形ですが、ここでは単なる「過去の能力」ではなく、「可能性（Possibility）」や「潜在的な能力（Potential ability）」のムード（法）を作ります。
  • have + 過去分詞: 英語において have + V3 は「完了」や「その時点までの状況」を表しますが、助動詞の後ろに置かれることで、焦点が「過去の特定の時点」に固定されます。
この二つが合体することで、「過去のある時点で、その行為を行うための能力や機会が存在していた」ことを示します。しかし、ここが最も重要なポイントですが、この形を使うとき、話し手は暗黙のうちに「しかし実際には行われなかった」という事実を前提にしています。
#### 2. 日本語との比較：ここが混乱のポイント！
日本語話者が最も苦労するのは、日本語の「できた」という言葉が持つ多義性です。日本語では、実際に行ったことも、行えた可能性も、どちらも「できた」で済ませてしまうことが多いからです。
  • 日本語: 「昨日は早く帰れた（から、実際に帰った）」
  • 日本語: 「昨日は早く帰れた（のに、残業した）」
英語では、これらを明確に使い分けます。
  • 事実（実際にやった）: I was able to leave early yesterday. または I managed to leave early.
  • 可能性（できたのにやらなかった）: I could have left early yesterday (but I didn't).
このように、could have は常に「反実仮想（事実に反する想定）」のニュアンスを含んでいます。日本語の「〜できたのに」という後悔や、「〜という可能性もあった」という推測に近い感覚で捉えると、理解がスムーズになります。
### Formation Pattern
could have + 過去分詞の形は、主語が何であっても変化しないため、パターン自体は非常にシンプルです。しかし、発音や短縮形において、日本人学習者が陥りやすい罠がいくつかあります。
#### 基本形
肯定文: 主語 + could have + 過去分詞 (V3)
否定文: 主語 + could not have (または couldn't have) + 過去分詞 (V3)
疑問文: Could + 主語 + have + 過去分詞 (V3)?
| 文の種類 | 構造 | 例文 |
| :--- | :--- | :--- |
| 肯定文 | Sub + could have + V3 | I could have told him the truth. (彼に真実を言うこともできたのに。)
| 肯定文（短縮） | Sub + could've + V3 | We could've won the game. (あの試合、勝てたはずだった。)
| 否定文 | Sub + could not have + V3 | He could not have known. (彼が知っていたはずがない。)
| 否定文（短縮） | Sub + couldn't have + V3 | It couldn't have been better. (これ以上はあり得ないほど最高だった。)
| 疑問文 | Could + Sub + have + V3? | Could you have finished it earlier? (もっと早く終わらせることはできたのですか？)
#### 形成上の注意点
  1. 1三人称単数でも has にならない:
日本語の学習者がよくやってしまうミスが、主語が He や She の時に He could has... としてしまうことです。助動詞 could の後ろは必ず動詞の原形が来るというルールがあるため、常に have です。He could have gone. が正解です。
  1. 1過去分詞のミス:
不規則動詞の過去分詞（V3）を正確に使う必要があります。例えば see なら seen、take なら taken です。could have saw のように過去形を使ってしまう間違いは、中級者でも意外と多いので注意しましょう。
  1. 1発音の落とし穴:
ネイティブスピーカーは会話で could have を could've と短縮し、さらにそれが「クダ（coulda）」のように聞こえることがあります。これが原因で、書き言葉でも could of と書いてしまうネイティブがいますが、これは重大な文法ミスです。皆さんは必ず could have または could've と書くようにしてください。
### When To Use It
この文法が使われる主なシチュエーションは5つあります。これらを意識的に使い分けることで、表現の幅が格段に広がります。
#### 1. 実現しなかった過去の能力・機会（Unrealized Ability/Opportunity）
「〜する能力や機会があったが、実際にはしなかった」という場合です。自分の選択や、状況の変化によって逃した機会について語る時に使います。
  • I could have gone to Harvard, but I chose to stay in Japan. (ハーバードに行くこともできたのですが、日本に留まることを選びました。)
  • We could have bought that house, but we waited too long. (あの家を買うこともできたのに、待ちすぎてしまった。)
#### 2. 過去の出来事に対する軽い非難・不満（Mild Criticism/Reproach）
相手が何かをしなかったことに対して、「〜することもできたはずだ（なぜしなかったのか）」と不満を伝える時に使います。should have（〜すべきだった）よりも少し柔らかい、あるいは皮肉めいた響きになることがあります。
  • You could have called me to say you were going to be late! (遅れるなら電話くらいできたでしょう！)
  • They could have at least offered to help. (少なくとも手伝うと申し出るくらいはできたはずだ。)
#### 3. 過去の可能性についての推測（Speculation about the Past）
「（証拠や論理から考えて）〜ということもあり得た」と推測する場合です。特に、何かが起こった原因を分析する際によく使われます。
  • The accident could have been much worse. (その事故は、もっとひどいことになっていた可能性もある。)
  • He's late. He could have missed the train. (彼は遅れている。電車に乗り遅れたのかもしれない。)
#### 4. 過去の強い否定・不可能の断定（Past Impossibility - Negative form）
否定形の couldn't have は非常に強力な表現で、「（どう考えても）〜だったはずがない」「〜することは不可能だった」という強い確信を伴う否定に使います。
  • She couldn't have stolen the money. She wasn't even in the office. (彼女がそのお金を盗んだはずがない。彼女はオフィスにさえいなかったのだから。)
  • I couldn't have finished the report without your help. (あなたの助けがなければ、レポートを完成させることは不可能でした。)
#### 5. 仮定法過去完了の帰結節（Third Conditional）
「もし〜だったら、〜できただろう」という仮定の話の一部として使われます。if 節が省略されることも多いです。
  • If I had had more time, I could have explored the city. (もっと時間があれば、街を散策できたのですが。)
  • (If you had asked,) I could have lent you some money. (言ってくれれば、お金を貸せたのに。)
### Common Mistakes
日本人学習者が特につまずきやすいポイントを、言語的な背景（L1転移）を踏まえて解説します。
#### 1. 「できた」をすべて could や was able to で訳してしまう
日本語では「（実際に）できた」も「（可能性として）できた」も同じ言葉を使うため、英語でも I could finish it. と言ってしまうことがよくあります。しかし、これでは単に「私はそれを終える能力があった」という過去の状態を述べているだけで、「（実際には終わらなかったが）終わらせることも可能だった」というニュアンスは伝わりません。
  • 間違い: I could go to the party yesterday, but I was tired.
  • 正しい: I could have gone to the party yesterday, but I was tired.
※ could have を使うことで、「行かなかった」という事実が明確になります。
#### 2. could have と should have の混同
どちらも「〜すればよかった」という日本語訳が当てはまることがあるため、混同されがちです。しかし、その根底にある感情が違います。
  • could have: 可能性に焦点を当てている。「〜することもできた（選択肢があった）」
  • should have: 義務や後悔に焦点を当てている。「〜すべきだった（しなかったのは間違いだった）」
例えば、就活（job hunting）で第一志望に落ちた友人に：
  • You could have applied to more companies. (もっと多くの会社に応募することもできたね。＝単なる選択肢の提示)
  • You should have applied to more companies. (もっと多くの会社に応募しておくべきだったね。＝反省やアドバイス)
#### 3. 否定形 couldn't have の意味の取り違え
couldn't have は「〜できなかった」という意味だけでなく、「〜だったはずがない（推測）」という意味で頻繁に使われます。これを単なる「能力の欠如」と解釈してしまうと、文脈を読み違えることになります。
  • It couldn't have been a mistake.
× 「それは間違いであることができなかった」
○ 「それが間違いだったなんて、あり得ない（絶対に間違いではない）」
### Contrast With Similar Patterns
似たような意味を持つ他の「法助動詞＋完了形」との違いを整理しましょう。ここをクリアにすることで、B2レベルの正確性が身につきます。
| 表現 | ニュアンス | 日本語のイメージ | 例文 |
| :--- | :--- | :--- | :--- |
| could have | 過去の可能性・能力 | 「〜できたのに」「〜もあり得た」 | I could have stayed longer. (もっと長居できたのに。)
| should have | 過去の義務・後悔 | 「〜すべきだった」「〜すればよかった」 | I should have stayed longer. (もっと長居すべきだった。)
| might have | 過去の不確かな推測 | 「〜だったかもしれない」 | I might have stayed longer. (もっと長居したかもしれないな。)
| must have | 過去の強い確信 | 「〜だったに違いない」 | He must have stayed longer. (彼はもっと長居したに違いない。)
ポイント:
  • could have は「能力や機会があったかどうか」に重点があります。
  • might have は could have よりも可能性が低く、単なる「推測」の響きが強くなります。
  • couldn't have（はずがない）の対義語は must have（に違いない）になります。
### Quick FAQ
Q: could have は「後悔」の気持ちが含まれますか？
A: 含まれることもありますが、必須ではありません。単に「別の可能性もあった」という客観的な事実を述べる時にも使います。強い後悔を表したい時は should have の方が適しています。
Q: could have と can have は使い分けますか？
A: 過去の可能性を語る場合、can have という形は使いません。常に could have を使います。can は現在や未来の可能性、could have は過去の（実現しなかった）可能性と覚えておきましょう。
Q: ビジネスメールで could have を使うのは失礼ですか？
A: 全く失礼ではありません。むしろ、トラブルの原因を分析する際などに「〜という可能性もあり得ました（It could have been caused by...）」のように、論理的な推論を述べる際に非常に重宝される丁寧な表現です。
Q: could have を使って「実際にできたこと」を言えますか？
A: いいえ、言えません。実際にできた（そしてやった）ことは、I was able to... や I managed to...、あるいは単に過去形を使って表現します。could have を使うと、聞き手は「あ、実際にはやらなかったんだな」と判断します。
---
最後に：先生からのメッセージ
could have + 過去分詞は、日本語の「〜できたのに」という少し切ない響きや、「〜だったかもしれない」という論理的な推察を、英語でスマートに表現するための鍵です。最初は「実際にやったこと」と「できたはずのこと」を区別して話すのに脳のトレーニングが必要かもしれませんが、意識して使ううちに、あなたの英語はより知的で、ニュアンス豊かなものに変わっていくはずです。頑張りましょう（頑張りましょう）！

Forming the Past Modal of Possibility

Subject Modal Auxiliary Past Participle (V3) Example
I / You / He / She
could
have
finished
I could have finished.
It / We / They
could
have
gone
They could have gone.
I / You / He / She
couldn't
have
known
She couldn't have known.
It / We / They
couldn't
have
seen
We couldn't have seen it.

Contractions and Pronunciation

Full Form Contraction Pronunciation (IPA) Common Misspelling
could have
could've
/ˈkʊdəv/
could of
could not have
couldn't have
/ˈkʊdənt əv/
couldn't of

Meanings

Expresses a past possibility or an ability that was not realized. It describes an alternative reality where something was possible but didn't occur.

1

Missed Opportunity

Something was possible, but you chose not to do it or it didn't happen.

“She could have been a doctor if she had stayed in school.”

“We could have taken the train, but we decided to drive.”

2

Past Guess/Possibility

Making a logical guess about something that might have happened in the past.

“Where is my phone? I could have left it at the office.”

“He's late. He could have gotten stuck in traffic.”

3

Polite Criticism

Telling someone they should have done something differently in the past.

“You could have told me you were going to be late!”

“They could have at least offered to help with the dishes.”

4

Past Impossibility

Using the negative form to say something was impossible even if someone tried.

“I couldn't have finished the work without your help.”

“He couldn't have stolen the car; he was with me all night.”

Reference Table

Reference table for 過去の可能性：〜できたのに (Could Have)
使い方 意味 Example Sentence
Possibility
可能だったけれど、起きなかったこと
I could have stayed longer.
Ability
能力はあったけれど、使わなかったこと
He could have won the race.
Criticism
誰かが違う行動をすべきだった、という批判
You could have told me!
Relief
悪い事態が危うく起こりそうだった、という安堵
That could have been a disaster.
Uncertainty
過去の出来事に対する推測や憶測
She could have forgotten.
Negative
何かは不可能だった、という否定
I couldn't have done it alone.

フォーマル度スペクトル

フォーマル
The assignment could have been completed by the deadline had circumstances differed.

The assignment could have been completed by the deadline had circumstances differed. (Work productivity)

ニュートラル
I could have finished the report on time.

I could have finished the report on time. (Work productivity)

カジュアル
I could've finished it, but I didn't bother.

I could've finished it, but I didn't bother. (Work productivity)

スラング
I coulda done it, man.

I coulda done it, man. (Work productivity)

「Could Have」の世界

Could Have

後悔

  • Studied I could have studied harder.
  • Called I could have called my mom.

逃したチャンス

  • Won We could have won the game.
  • Gone I could have gone to Paris.

過去の可能性 vs. 過去の能力

一般的な能力 (Could)
I could swim. I knew how to swim when I was 5.
特定の逃した機会 (Could Have)
I could have swum. I had the chance to swim today, but I didn't.

「Could Have」を使うべき？

1

それは過去に起こりましたか？

YES
次のステップへ
NO
現在形または「can」を使う。
2

可能だったのに、起きませんでしたか？

YES
「Could Have」を使いましょう！
NO ↓

「Could Have」でよく使う過去分詞

🏠

日常生活

  • • Been
  • • Done
  • • Gone
  • • Seen
📱

コミュニケーション

  • • Told
  • • Said
  • • Written
  • • Called
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レベル別の例文

1

I can play soccer.

I have the ability now.

2

Can you help me?

Are you able to help?

3

He can speak English.

He knows how to speak it.

4

They can't come today.

They are not able to come.

1

I could swim when I was five.

I had the skill in the past.

2

We could see the mountains from our room.

It was possible to see them.

3

She could not find her keys yesterday.

She failed to find them.

4

Could you open the window?

A polite request.

1

I could have helped you if you asked.

I had the ability, but you didn't ask.

2

He could have been late because of the rain.

Maybe the rain made him late.

3

You could have told me the news!

I am a bit annoyed you didn't tell me.

4

We could have bought that house, but it was too expensive.

It was a possibility we rejected.

1

The accident could have been much worse.

It was possible for it to be worse, but it wasn't.

2

He couldn't have committed the crime; he was abroad.

It was impossible for him to do it.

3

I could have sworn I left my wallet on the table.

I am almost certain, but I might be wrong.

4

They could have at least sent a thank-you note.

Expressing social expectation/criticism.

1

Had we known the risks, we could have mitigated the damage.

Speculating on a complex past scenario.

2

She could have been being followed for weeks without knowing.

Past continuous possibility.

3

The project could hardly have been more successful.

It was extremely successful (idiomatic).

4

You could have heard a pin drop in that room.

It was very quiet (idiom).

1

One could have been forgiven for thinking the war was over.

A sophisticated way to describe a common mistake.

2

The implications could not have been more profound.

The effects were very deep.

3

He could have done with a bit more support from his peers.

He needed more support (British idiom).

4

The play could have done without the long intermission.

The intermission was unnecessary.

間違えやすい

Past Possibilities (Could Have) 対 Could Have vs. Should Have

Learners mix up possibility (could) with obligation (should).

Past Possibilities (Could Have) 対 Could Have vs. Must Have

Both are used for guessing, but 'must have' is for 90% certainty.

Past Possibilities (Could Have) 対 Could Have vs. Might Have

They are very similar, but 'could' emphasizes the 'ability' aspect.

よくある間違い

✗

I can went.

✓

I could go.

A1 learners often mix 'can' with past tense verbs.
✗

I could have go.

✓

I could have gone.

Using the base form instead of the past participle.
✗

I could of seen it.

✓

I could have seen it.

Writing 'of' because it sounds like the contraction 've'.
✗

I could have finish.

✓

I could have finished.

Forgetting the -ed ending on regular past participles.
✗

He could has gone.

✓

He could have gone.

Trying to conjugate 'have' for the third person. Modals are always followed by the base 'have'.
✗

I could have been able to go.

✓

I could have gone.

Redundancy. 'Could' already implies 'able to'.

文型パターン

I could have ___ if I had ___.

You could have ___!

It could have been ___.

They couldn't have ___ without ___.

Real World Usage

Job Interviews common

I could have stayed at my last job, but I wanted a new challenge.

Texting Friends very common

U could've told me u were bringing pizza!

Police Reports occasional

The suspect could have entered through the window.

Sports Commentary constant

He could have scored there if he'd taken the shot earlier!

Doctor's Office common

It could have been a virus, but the tests were negative.

Travel/Tourism common

We could have seen the Eiffel Tower if we hadn't missed the bus.

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⚠️

「Could Of」という落とし穴！

「could of」と書くのは絶対にやめましょう。発音は「could've」と似ていますが、文法的には完全に間違いです。「could have」と必ず書きましょうね。
I could have gone.
🎯

発音の秘密！

英語を速く話す時、「could have」は「could-uh」のように聞こえることがあります。ネイティブスピーカーは、両方の単語をはっきりと発音することはめったにありませんよ。 "I could've done it."
💡

動詞は過去分詞形だけ！

「could have」の後ろには、必ず動詞の3番目の形、つまり過去分詞形を使います。「could have taken」のように、「could have took」ではありませんよ。
He could have seen it.

Smart Tips

Use 'You could have...' instead of 'Why didn't you...?' It sounds more like a suggestion than an attack.

Why didn't you tell me? → You could have told me!

Never use the contraction 'could've'. Always write out 'could have' to maintain a professional tone.

The results could've been better. → The results could have been better.

Don't copy it! The actor is saying 'could've'. Always remember the 'have' in your mind.

I could of gone. → I could have gone.

Use 'could have' to brainstorm multiple possibilities. It shows you are thinking critically.

He forgot. → He could have forgotten, or he could have lost his phone.

発音

could-uv

The 've' reduction

In 'could have', the 'have' is almost never stressed. It reduces to /əv/.

kʊ-dəv

The 'd' link

The 'd' in 'could' often links directly to the 'h' or 'a' sound in 'have'.

Criticism Intonation

You could have TOLD me! ↗️

Rising pitch on the verb to show annoyance.

暗記しよう

記憶術

Remember: 'Could Have' is for the 'Could-a, Would-a, Should-a' family of regrets.

視覚的連想

Imagine a fork in a road. You are standing on the right path, looking back at the left path you didn't take. That left path is the 'Could Have' path.

Rhyme

If it didn't take place, but there was space, use 'could have' to state the case.

Story

A man missed his bus. He thinks, 'I could have woken up earlier.' Then he sees a car crash where the bus would have been. He thinks, 'I could have been in that crash!' He feels lucky he missed it.

Word Web

could'vepast participleregretpossibilityspeculationopportunityunreal

チャレンジ

Write down three things you could have done this morning but chose not to (e.g., 'I could have stayed in bed').

文化メモ

British speakers often use 'could have' for very polite, indirect criticism to avoid sounding aggressive.

In casual American speech, 'coulda' is extremely common and often used in a self-deprecating way about missed sports or career goals.

Using 'could have' to express relief after a dangerous situation is a common social bonding behavior.

Derived from Old English 'cuðe' (past of 'cunnan', to know/be able).

会話のきっかけ

“

What is something you could have done differently in your last job?

“

If you had won the lottery last year, what could you have bought?

“

Think of a famous historical event. How could it have ended differently?

“

Could you have imagined living in this city ten years ago?

日記のテーマ

Write about a 'near miss' or a lucky escape you had. What could have happened?
Reflect on a major decision you made. What were the other options? What could have happened if you chose differently?
Write a short mystery story where a detective speculates about how a thief could have entered a locked room.
Describe a time you were annoyed with a friend. What could they have done to make the situation better?

よくある間違い

Incorrect

正解

Incorrect

正解

Incorrect

正解

Incorrect

正解

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Test Yourself

正しい形に空欄を埋めましょう。

I ___ have bought that laptop, but I saved my money instead.

✓ Correct! ✗ Not quite. Correct answer: could
過去の可能性には「could + have + 過去分詞」を使います。
この文の間違いを見つけて修正しましょう。 Error Correction

Find and fix the mistake:

They could have went to the concert last night.

✓ Correct! ✗ Not quite. Correct answer: They could have gone to the concert last night.
「go」の過去分詞形は「gone」であり、「went」ではありません。
文法的に正しい文はどれでしょう？ 選択問題

最適な選択肢を選びましょう:

✓ Correct! ✗ Not quite. Correct answer: She could have called me.
この構文では、常に「have」を使い、「of」や「has」は使いません。

Score: /3

練習問題

8 exercises
Fill in the blank with the correct form of 'could have' and the verb in parentheses.

I ________ (buy) that dress, but it was too expensive.

✓ Correct! ✗ Not quite. Correct answer: could have bought
We use 'could have' + the past participle 'bought'.
Choose the sentence that means the action DID NOT happen. 選択問題

Which sentence implies the person stayed home?

✓ Correct! ✗ Not quite. Correct answer: I could have gone to the party.
'Could have' implies a missed opportunity.
Find the error in the following sentence. Error Correction

Find and fix the mistake:

He could of told us he was coming.

✓ Correct! ✗ Not quite. Correct answer: of
It should be 'have', not 'of'.
Rewrite the sentence using 'couldn't have'. Sentence Transformation

It was impossible for her to see us in the dark.

✓ Correct! ✗ Not quite. Correct answer: She couldn't have seen us.
'Couldn't have' + V3 expresses past impossibility.
Complete the dialogue. Dialogue Completion

A: I'm so sorry I'm late! B: It's okay, but you ________ (call) me.

✓ Correct! ✗ Not quite. Correct answer: could have called
This is a case of polite criticism for a past event.
Is this 'Possibility' or 'Impossibility'? Grammar Sorting

Sentence: 'He couldn't have known about the surprise.'

✓ Correct! ✗ Not quite. Correct answer: Impossibility
'Couldn't have' indicates something was not possible.
Match the situation to the 'could have' response. Match Pairs

Situation: You missed the bus.

✓ Correct! ✗ Not quite. Correct answer: I could have walked.
Walking is an alternative to taking the bus.
Which modal expresses a guess about the past? 選択問題

Where is Sarah? She ________ (leave) early.

✓ Correct! ✗ Not quite. Correct answer: could have left
'Could have' is used for making guesses about past events.

Score: /8

Practice Bank

10 exercises
文を完成させましょう。 穴埋め問題

We could ___ stayed at a nicer hotel if we had more money.

✓ Correct! ✗ Not quite. Correct answer: have
間違いを特定しましょう。 Error Correction

You could have did the homework earlier.

✓ Correct! ✗ Not quite. Correct answer: You could have done the homework earlier.
単語を正しい順序に並べ替えましょう。 Sentence Reorder

have / they / arrived / earlier / could

✓ Correct! ✗ Not quite. Correct answer: They could have arrived earlier.
この文を英語に翻訳しましょう。 翻訳

Podrías haber ganado.

✓ Correct! ✗ Not quite. Correct answer: You could have won.
過去に起きなかった可能性を表すのはどれでしょう？ 選択問題

正しい意味を選びましょう:

✓ Correct! ✗ Not quite. Correct answer: I could have traveled to Japan.
状況と「could have」の正しい文を組み合わせましょう。 Match Pairs

組み合わせましょう:

✓ Correct! ✗ Not quite. Correct answer: I could have left earlier.
否定形を埋めましょう。 穴埋め問題

I ___ have passed without your help.

✓ Correct! ✗ Not quite. Correct answer: Both are correct
助動詞を修正しましょう。 Error Correction

He could has been a doctor.

✓ Correct! ✗ Not quite. Correct answer: He could have been a doctor.
単語を並べ替えましょう。 Sentence Reorder

could / she / been / have / better

✓ Correct! ✗ Not quite. Correct answer: She could have been better.
正しい否定の構文を選びましょう。 選択問題

正しい文を選びましょう:

✓ Correct! ✗ Not quite. Correct answer: I couldn't have known.

Score: /10

よくある質問 (8)

They are often the same when guessing. However, `could have` also means you had the *ability* to do something but didn't, while `might have` is strictly about *probability*.

Because the contraction `could've` sounds exactly like 'could of'. It is a spelling error, never a grammatical truth.

No. If it happened, use the simple past or 'was able to'. `Could have` is for things that *didn't* happen.

It means something was impossible. 'I couldn't have done it' means even if I tried, it was not possible.

It is neutral. It is used in both casual conversation and formal writing.

No. Modals like `could` are always followed by the base form `have`. Never use 'could has'.

`Could have` is about possibility/ability. `Should have` is about what was the right or smart thing to do.

Yes! It is used in the Third Conditional: 'If I had known, I could have helped.'

Scaffolded Practice

1

1

2

2

3

3

4

4

Mastery Progress

Needs Practice

Improving

Strong

Mastered

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In Other Languages

Spanish high

Podría haber + participio

Spanish speakers often use the preterite 'pudo' for things that actually happened, whereas English uses 'was able to'.

French moderate

Aurait pu + infinitif

French follows this with an infinitive, while English uses a past participle.

German moderate

Hätte ... können

The word order is significantly different, with the modal verb moving to the end.

Japanese low

〜できたはずだ (dekita hazu da)

Japanese doesn't have a direct 'modal perfect' equivalent; it relies on context and sentence-ending particles.

Arabic partial

كان بإمكانه أن (kāna bi-imkānihi 'an)

Arabic structure is more periphrastic (uses more words) than the English modal.

Chinese partial

本来可以 (běnlái kěyǐ)

Chinese has no verb conjugation or 'have' auxiliary for this meaning.

Learning Path

Prerequisites

Previous
好みを表明する: Would Rather
Next
過去の推測：Might Have（〜したかもしれない）

Learn These First

B1 Requires

Could: 過去のスキルについて話す

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過去完了形: 「以前の」過去 (had + done)

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