Translation guide
Expressing inability to perform an action in Japanese. The most common pattern uses the potential form of verbs, often with できない or other negative potential forms. There are also set phrases and grammar patterns for formal or written contexts.
Express that one is unable to perform an action due to lack of ability, circumstances, or permission.
The most common way to say 'cannot do' is to use the negative potential form of a verb. For ru-verbs, replace る with られない; for u-verbs, change the final -u to -e and add ない. する becomes できない, and くる becomes こられない.
The negative potential form of する (to do). Used for 'cannot do' in a general sense, or when the verb is する.
宿題ができない。
I can't do my homework.
そんなことできない。
I can't do such a thing.
A more formal or written pattern meaning 'cannot do'. It uses the nominalizer こと to turn the verb into a noun phrase, followed by ができない.
彼は納豆を食べることができない。
He cannot eat natto.
私は車を運転することができない。
I cannot drive a car.
A literary or formal pattern meaning 'cannot possibly do'. Attaches to the masu-stem of verbs. Often used in written language.
それはあり得ない。
That's impossible. / That can't be.
彼の成功は望み得ない。
His success cannot be hoped for.
Express that one is unable to do something because of a situation, rules, or external factors, not personal ability.
Used to say that one must not do something, or that it is not allowed. Often implies a prohibition or rule.
ここで写真を撮ってはいけない。
You cannot take photos here.
授業中に寝てはいけない。
You must not sleep during class.
Means 'cannot do' due to social, moral, or situational constraints. It implies that doing so would be against one's principles or the situation does not allow it.
約束を破るわけにはいかない。
I can't break my promise.
ここで諦めるわけにはいかない。
I can't give up here.
Same pattern as above, but used when the inability is due to external factors rather than personal skill.
雨で試合をすることができない。
We can't play the match because of rain.
Express that no matter how hard one tries, the action cannot be accomplished.
Emphasizes that even if one attempts the action, it is impossible. Often used with どうしても or いくら...ても.
どうしても思い出せない。
I just can't remember.
いくら練習しても上手にできない。
No matter how much I practice, I can't do it well.
Means 'there is no way to do' or 'cannot be done'. Indicates a lack of method or means.
この機械は直しようがない。
This machine cannot be fixed.
彼の行き先は知りようがない。
There's no way to know where he went.
Express that one is emotionally or mentally unable to do something.
Literary expression meaning 'cannot bear to do'. Used for strong emotional inability.
その光景は見るに耐えない。
That sight is unbearable to watch.
Softens the statement by expressing a feeling of inability, often used for psychological reasons.
今日は仕事に行けない気がする。
I feel like I can't go to work today.
できない is the casual, everyday form. ことができない is more formal and often used in writing or polite speech. Both express inability, but ことができない can sound more objective or definitive.
彼は泳げない。
He can't swim. (casual)
彼は泳ぐことができない。
He cannot swim. (formal)
English 'be unable to' is often translated directly as できない or potential negative. However, in Japanese, the potential form itself already carries the meaning of ability/inability, so adding extra words like 不能 is usually unnatural.
彼は来られない。
He is unable to come.
日本語が話せない。
I can't speak Japanese.
彼女はパーティーに来られなかった。
She couldn't come to the party.
この提案を受け入れることはできません。
We cannot accept this proposal.