Grammar Rule in 30 Seconds
Use 'could' to describe general talents or skills you had in the past, like speaking a language or swimming.
- Use 'could' for general past abilities: 'I could run fast.'
- Use 'couldn't' for all past failures: 'I couldn't find my keys.'
- Never add -s, -ed, or -ing to 'could' or the main verb.
Overview
could だ。これは英文法のタイムマシンみたいなもの。膝がきしまず、TikTokの下書き（drafts）なんて存在しなかった時代に、君のスキルを連れ戻してくれるんだ。このルールは「一般的な能力（general ability）」に関するもの。長い期間にわたってやり方を知っていたことについてだ。子供の頃の趣味、昔の仕事、あるいは数学が実際に理解できていたあの時期の話だ。シンプルで、パンチが効いていて、自分の人生のストーリーを語るのに欠かせない。ただ、ディナーパーティーで自慢しすぎないようにね。2012年のMinecraftサーバーの話を止めない「過去の栄光（could-have-been）」おじさんなんて、誰も好きじゃないからね。How This Grammar Works
could は can の、リラックスした兄貴分だと思ってほしい。can が「今、ここ」の対応で忙しくしている間、could は過去でまったりしている。最高な点は？これが助動詞（modal verb）だってこと。英文法の世界では、「modal」はたいてい「使いやすい」って意味だ。なぜかって？助動詞は驚くほど怠け者だからさ。誰のためにも形を変えたりしない。自分について話そうが、親友について話そうが、K-POPの熱狂的ファン（stans）の集団について話そうが、could は全く同じままだ。三人称のために s を足す必要はない。過去形にするために ed を足す必要もない（すでに過去だから！）。メインのアクションワード（動詞）の直前に置くだけだ。これはヘルパーのような役割を果たし、そのアクションに「過去の能力」という風味を加える。一つ覚えておいてほしいこと：could の後に続く動詞は、最もシンプルな形（原形）でなければならない。to も、-ing も、派手な語尾も絶対にダメ。「ミニマリストの服装」みたいなものだ。清潔で、機能的で、失敗しようがない。サンダルに靴下を合わせようとしない限りはね。それはまた別の種類の間違いだ。
Formation Pattern
could を使った文を作るのは、アプリでピザを注文するより簡単だ。必要なのは3つの主な材料だけ。以下のステップに従って文を組み立てよう：
could を足す（できなかったことなら couldn't）。
could swim. | 私は泳げた。
couldn't dance. | 君は踊れなかった。
Could she sing? | 彼女は歌えた？
Couldn't they see? | 彼らは見えなかったの？
could が一度も変化していないことに気づいた？ I could、She could、The dog could。究極のチームプレーヤーだ。否定の場合、could not を使うけど、ほとんどの人は couldn't に短縮する。そのほうが自然に聞こえるし、Instagramをスクロールするための貴重な数ミリ秒を節約できるからね。質問したい場合は、主語と could を入れ替えるだけ。プロっぽく聞こえるシンプルな入れ替え術（switcheroo）だ。ただ、クエスチョンマークを忘れないで。そうしないと、すごく混乱した独り言を言っているだけだと思われるかもしれないから。
When To Use It
could を使う。第一に、「一般的な能力」について。これは、やりたいときにいつでもできたことを意味する。「I could speak French when I lived in Paris.（パリに住んでいた頃、フランス語が話せた。）」一度だけ話せたわけじゃない。数ヶ月、あるいは数年にわたってそのスキルを持っていたんだ。第二に、「感覚（senses）」の動詞に使う。これらは see、hear、smell、taste、feel のような単語だ。もしコンサートにいて、音楽が胸に響いていたら、「I could feel the bass.（低音が感じられた。）」と言うだろう。第三に、「精神的な（mental）」プロセスに使う。複雑な数学の問題を見つめていて、突然ピンときたなら、それを理解できた（You could understand it）ということだ。could last for a week on one charge.（僕の古いノキアは1回の充電で1週間もった。）」これは一般的な能力だ。あるいは、昔遊んでいたテレビゲームを思い出して。「I could beat the final boss in ten minutes.（ラスボスを10分で倒せた。）」それは君が持っていたスキルだ。重要なのは、何かをする力を持っていたという「バイブス（vibe）」だ。まさにその瞬間にそれをしていたという意味ではない。ただ可能性（potential）があったということだ。たとえ今、ポテチの袋を抱えてソファに寝転がっていても、ジムに行く「可能性」はあるのと同じようにね。
Common Mistakes
could の後に to を足してしまうことだ。「I could to play guitar」と言ってしまうのをよく耳にする。これは絶対にダメ（big no-no）。could と to は、泥沼の別れ方をした2人の有名人だと思ってほしい。同じ部屋にいることはできないんだ。いつだって could play であり、決して could to play ではない。could を使うことだ。もし昨日、無くしたAirPodsを見つけられたとしても、「I could find them」とは言うべきじゃない。could は一般的なスキルのためのもので、特定の「やったぜ！」という瞬間のためのものではない。そういう一回限りの勝利には、通常 was able to や managed to を使う。couldn't は万能の修理屋（universal fixer）だということを忘れないで。could が「一般的 vs 特定」にうるさいのに対し、couldn't は気にしない。「一般的なスキルの欠如（I couldn't swim as a kid - 子供の頃は泳げなかった）」にも、「特定の失敗（I couldn't find the link for the Zoom call today - 今日Zoom会議のリンクが見つけられなかった）」にも使える。これは過去の「不可能」におけるスイスアーミーナイフだ。賢く使おう。でも悲観的に聞こえすぎないようにね。「あれもできない、これもできない」ダニー（couldn't-do-it Danny）なんて誰も好きじゃないから。Contrast With Similar Patterns
Could vs Was able to だ。双子のように見えるけど、性格は違う。Couldは、一般的で長期的な能力に使う。（例：I
- 学校では速く走れた。）couldrun fast in school.Was able toは、特定の、一回限りの達成に使う。（例：I
- 午後5時までにレポートを終わらせることができた。）was able tofinish the report by 5 PM.
Could は君の才能。Was able to は君の特定の勝利。「I could open the jar」と言えば、瓶を開ける生涯の才能を持っていたように聞こえる。「I was able to open the jar」と言えば、その特定の瓶は手ごわかったけど、君が勝った（開けられた）ように聞こえる。Used to を比べてみよう。Used to は「習慣」に焦点を当てているのに対し、could は「能力」に焦点を当てている。「I used to swim」は、よくプールに行っていたという意味。「I could swim」は、どうやって浮くかを知っていたという意味だ。これらを一緒に使えば、懐かしさMAX（maximum nostalgia）だ。「I used to go to the beach because I could swim well.（泳ぐのが得意だったから、よくビーチに行っていた。）」これは「あの頃は良かった」のダブルショットみたいなものだね。Quick FAQ
could は過去のことだけ？
ほとんどそうだけど、現在の丁寧な依頼にも使うよ（
Could you help me?死んだ人にも could を使っていい？
うん。歴史上の人物について話すなら、could を使うことになる。「Einstein could solve complex equations in his head.（アインシュタインは複雑な方程式を頭の中で解くことができた。）」
couldn't と can't の違いは？
Can't は今のこと。Couldn't はあの頃のこと。「I can't find my phone now, but I couldn't find my keys yesterday.（今はスマホが見つからないけど、昨日は鍵が見つからなかった。）」
did のような助動詞は必要？
いいや！ Could は強くて独立的だ。「I did could」とは言わない。ただ「I could」だ。バックバンドを必要としないソロアーティストみたいなものさ。
2. Negative Contractions
| Full Form | Contraction | Usage |
|---|---|---|
|
could not
|
couldn't
|
Common in speech and informal writing
|
|
could not
|
n/a
|
Used for formal emphasis
|
Conjugation of 'Could' for Past Ability
| Subject | Modal | Base Verb | Example |
|---|---|---|---|
|
I
|
could
|
swim
|
I could swim.
|
|
You
|
could
|
swim
|
You could swim.
|
|
He/She/It
|
could
|
swim
|
She could swim.
|
|
We
|
could
|
swim
|
We could swim.
|
|
They
|
could
|
swim
|
They could swim.
|
Meanings
Used to describe a general ability or skill that someone possessed in the past but may not possess now.
General Past Ability
A skill you had over a long period, like a talent or a language.
“She could speak three languages by the age of ten.”
“My grandfather could play the violin beautifully.”
Past Inability (Negative)
Used to say that someone was not able to do something, whether it was a general skill or a specific event.
“I couldn't swim until I was twelve.”
“We couldn't find the restaurant last night.”
Past Permission (Reported)
Used to describe being allowed to do something in the past.
“When we were kids, we could stay up late on Fridays.”
“I could wear whatever I wanted at my old job.”
Reference Table
| 使い方 | 形 | 例文 | 日本語訳 |
|---|---|---|---|
|
一般的な能力
|
Subject + could + Base Verb
|
When I was young, I could climb trees.
|
子供の頃、木登りができました。
|
|
否定的な能力
|
Subject + couldn't + Base Verb
|
She couldn't understand the lecture.
|
彼女はその講義を理解できませんでした。
|
|
質問 (能力)
|
Could + Subject + Base Verb?
|
Could you speak Spanish in high school?
|
高校生の時、スペイン語を話せましたか？
|
|
特定の成功 (🚫)
|
Subject + was/were able to + Verb
|
I was able to find my keys eventually.
|
最終的に鍵を見つけることができました。
|
|
知覚
|
Subject + could + Perception Verb
|
We could hear the ocean from our room.
|
私たちの部屋からは海が聞こえました。
|
|
過去の習慣 (代替)
|
Subject + used to be able to + Verb
|
I used to be able to run faster.
|
もっと速く走れました。
|
フォーマル度スペクトル
I possessed the ability to converse in French during my residency. (Professional vs Social)
I could speak French when I lived there. (Professional vs Social)
I used to be able to do French pretty well. (Professional vs Social)
I was lowkey fluent in French back in the day. (Professional vs Social)
Could（過去の能力）
使用例
- 一般的なスキル I could play piano.
- 知覚 I could hear the rain.
- 否定的な行動 I couldn't finish it.
形
- 肯定形 Subject + could + Base Verb
- 否定形 Subject + couldn't + Base Verb
- 疑問形 Could + Subject + Base Verb?
主な対比
- vs. Was/Were Able To `Could` (一般的な能力), `Was/Were Able To` (特定の成功)
Could と Was/Were Able To の比較
Could または Was/Were Able To の選び方
過去の「一般的な能力やスキル」について話していますか？
過去の「特定の、成功した行動」、特に困難だったことについて話していますか？
過去の不能についての「否定」の文ですか？（一般的または特定）
Could：説明できること
子どもの頃の才能
- • Could draw well
- • Could sing high notes
- • Could solve Rubik's Cube
過去の職業・趣味
- • Could code in Python
- • Could run marathons
- • Could bake intricate cakes
感覚能力
- • Could hear whispers
- • Could see in the dark
- • Could feel vibrations
実現しなかった可能性
- • Could have learned Spanish
- • Could have traveled more
- • Could have started a business
レベル別の例文
I could run very fast when I was a boy.
She could not swim last year.
Could you speak English in 2010?
They could play football well.
My sister could read when she was four years old.
We couldn't hear the teacher because of the noise.
Could your father drive a truck?
I could see the stars clearly from my balcony.
I could speak Italian fluently when I lived in Rome.
He couldn't finish the exam because it was too hard.
Even though I was tired, I was able to reach the summit.
Could you understand the local dialect when you visited Scotland?
As soon as I walked into the kitchen, I could smell the fresh bread.
In the 19th century, people could travel across the Atlantic by steamship.
She said she could lend me the money if I needed it.
I couldn't help but notice how nervous he was.
The athlete could have won the race, but he tripped at the last moment.
Only after hours of searching could we find the hidden entrance.
He could be quite difficult to work with in those days.
The complexity was such that few could comprehend the implications.
The sheer scale of the disaster was something no one could have predicted.
It was a time when one could still find solitude in the city's hidden parks.
Whether he could actually perform under such pressure remained to be seen.
The manuscript was so damaged that the scholars could barely decipher the script.
間違えやすい
Learners use 'could' for specific successes because their native language uses one word for both.
Learners mix up past ability with past possibility.
Both are used for the past, but 'would' is for habits, not abilities.
よくある間違い
I could to swim.
I could swim.
He coulds play.
He could play.
I can swim yesterday.
I could swim yesterday.
I no could go.
I couldn't go.
I coulded speak.
I could speak.
Did you could see?
Could you see?
I couldn't to hear.
I couldn't hear.
I could win the race yesterday.
I managed to win the race yesterday.
We could find the house finally.
We were able to find the house finally.
I could spoke English.
I could speak English.
I could have swam.
I could have swum.
文型パターン
When I was ___, I could ___.
I couldn't ___ because ___.
I searched everywhere, but I couldn't ___.
Back in the day, people could ___ without ___.
Real World Usage
In my last role, I could handle high-pressure situations effectively.
Throwback to when I could actually do a flip!
I could see the suspect running toward the park.
We couldn't find the hotel, so we asked a local for help.
Before the surgery, I couldn't walk for more than ten minutes.
Your grandfather could eat a whole turkey by himself!
過去の能力チェックリスト
was/were able toに切り替えましょう。
If it was a one-time success, especially against odds, switch to was/were able to.意味を混同しないで！
couldn'tは柔軟に使える
英語の繊細なニュアンス
was/were able toを使い分けるのは、とても微妙ですが、自然な英語を話すためには重要です。この使い分けをマスターすると、英語の深いニュアンスを理解していると評価されますよ。
Mastering it shows a deeper grasp of English nuance, which can impress in professional or academic settings.
Smart Tips
Swap 'could' for 'managed to' to sound like a native speaker.
Always use 'could' instead of 'was able to' for a more natural flow.
Relax! 'Could' is the same for everyone (I, you, he, she, they).
Use 'could not' instead of 'couldn't' to add weight and formality to your writing.
発音
Silent L
The 'l' in 'could' is completely silent. It sounds exactly like 'good' but with a 'k' sound.
Weak Form
In fast speech, 'could' is often reduced to a very short sound.
Couldn't Glottal Stop
In many dialects, the 't' in 'couldn't' is replaced by a glottal stop.
Rising Intonation in Questions
Could you ↗swim?
Conveys a polite inquiry about a past skill.
暗記しよう
記憶術
C.O.U.L.D. = Capability Over Us Last Decade.
視覚的連想
Imagine a younger version of yourself wearing a superhero cape. On the cape, the word 'COULD' is written. Think of all the things that 'super-you' was able to do back then.
Rhyme
When I was young and life was good, I did all the things I could.
Story
In the Kingdom of Yesterday, everyone had a 'Could-Card.' If you had a talent for years, like singing, your card said 'I could sing.' But if you only did something once, like finding a lost ring, the card said 'I managed to find it.'
Word Web
チャレンジ
Write down three things you could do when you were ten years old that you cannot do now.
文化メモ
British speakers often use 'could' with 'at all' to emphasize inability: 'I couldn't see it at all.'
Americans frequently substitute 'could' with 'was able to' in casual stories to sound more dynamic.
In academic writing, 'could' is used to describe historical possibilities or theories that were once held.
From Old English 'cuðe', the past tense of 'cunnan' (to know or be able).
会話のきっかけ
What is something you could do as a child that you can't do now?
Could you speak any other languages when you were younger?
Think of a difficult situation you faced last year. Could you solve it alone?
If you could go back in time, what skill do you wish you could have learned earlier?
日記のテーマ
よくある間違い
Test Yourself
When I was five, I ___ read simple books.
Find and fix the mistake:
Yesterday, I could finish all my homework, even though it was a lot.
was/were able toの方が適切です。
Choose the correct sentence:
toなしで続きます。Translate into English: "Als Kind konnte sie stundenlang tanzen."
Answer starts with: ["A...
Als KindはAs a childと翻訳され、「konnte」（could）は「tanzen」（dance）を「stundenlang」（for hours）できた彼女の一般的な過去の能力を表します。Score: /4
練習問題
8 exercisesWhen I was a child, I ___ speak German fluently.
Find and fix the mistake:
He could to play the guitar when he was young.
The exam was very difficult, but I ___ pass it.
I can't hear you.
We use 'could' for specific one-time successes in affirmative sentences.
A: Did you find your keys? B: Yes, I ___ find them under the sofa.
Sort these sentences.
Match 'I can' and 'I can't'.
Score: /8
Practice Bank
12 exercisesBefore the accident, he ___ lift heavy weights easily.
After days of searching, they finally could locate the lost treasure.
Which sentence correctly expresses general past ability?
Translate into English: "Trotz des schlechten Wetters konnten wir den Gipfel erreichen."
これらの単語を並べ替えて文を作りましょう：
主語と過去の能力の正しい形を組み合わせましょう：
Before smartphones, people ___ remember many phone numbers by heart.
I tried to download the app, but I could not doing it.
Which sentence correctly expresses a general past ability?
Translate into English: "Könnten Sie als Kind gut zeichnen?"
これらの単語を並べ替えて文を作りましょう：
不能のシナリオと最も適切な動詞の形を組み合わせましょう：
Score: /12
よくある質問 (8)
Generally, no. In affirmative sentences, use `managed to` or `was able to` for specific events. However, you can use `couldn't` for specific failures.
`Could` is for general skills (like 'I could swim'). `Was able to` is for both general skills and specific moments (like 'I was able to escape').
No. Never use `to` after `could`. Say `I could go`, not `I could to go`.
Not necessarily. `Could` is very common in all registers. `Was able to` can sound slightly more formal or precise in specific contexts.
No. Modal verbs like `could` never change their form. It is always `could` for all subjects.
Verbs of the senses (see, hear, smell) are an exception. We often use `could` with them even for specific moments: `I could see him clearly.`
Move `could` to the front of the sentence: `Could you speak English ten years ago?`
Yes! While affirmative `could` is for general ability, negative `couldn't` works for both general and specific situations.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
podía / pude
English uses 'couldn't' for both, while Spanish still chooses between 'no podía' and 'no pude'.
pouvais / ai pu
French uses the auxiliary 'avoir' for specific past ability, while English uses 'was able to'.
konnte
German is more flexible with 'konnte' for specific events than English is with 'could'.
できた (dekita)
Japanese doesn't have a separate modal word like 'could'; the ability is built into the verb ending.
كان يستطيع (kana yastati')
Arabic requires two verbs to express what English does in one word ('could').
会 (huì) / 能 (néng) + past context
Chinese relies on time markers rather than a specific past-tense modal verb.
Learning Path
Prerequisites
Learn These First
Continue With
関連動画
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