Can / Cannot in Korean — -(으)ㄹ 수 있다/없다 and 못

<h2>"Can You Speak Korean?" — The Question That Changes Everything</h2> <p>After a few months in Seoul, the question I heard most often was "한국어 할 수 있어요?" (hangugeo hal su isseoyo? — Can you speak Korean?). This sentence contains THE most important grammar structure for expressing ability: <strong>-(으)ㄹ 수 있다</strong>. Mastering this construction means being able to say everything you can do, and everything you can't (yet) do.</p> <h2>Ability: -(으)ㄹ 수 있다 — "Can / Know How To"</h2> <p>To say "I can" or "I know how to," use the verb stem + <strong>-(으)ㄹ 수 있다</strong>.</p> <h3>Construction Rule</h3> <table> <tr><th>Stem ending</th><th>Addition</th><th>Example</th><th>Result</th></tr> <tr><td>Vowel</td><td>-ㄹ 수 있다</td><td>가다 → 가</td><td>갈 수 있다</td></tr> <tr><td>Consonant</td><td>-을 수 있다</td><td>먹다 → 먹</td><td>먹을 수 있다</td></tr> <tr><td>ㄹ final</td><td>-ㄹ 수 있다 (ㄹ stays)</td><td>만들다 → 만들</td><td>만들 수 있다</td></tr> </table> <h3>Conjugated Examples (Polite Form)</h3> <table> <tr><th>Verb</th><th>Ability</th><th>Romanization</th><th>Translation</th></tr> <tr><td>하다 (to do)</td><td>할 수 있어요</td><td>hal su isseoyo</td><td>I can do</td></tr> <tr><td>[가다](/en/dictionary/%EA%B0%80%EB%8B%A4) (to go)</td><td>갈 수 있어요</td><td>gal su isseoyo</td><td>I can go</td></tr> <tr><td>먹다 (to eat)</td><td>먹을 수 있어요</td><td>meogeul su isseoyo</td><td>I can eat</td></tr> <tr><td>읽다 (to read)</td><td>읽을 수 있어요</td><td>ilgeul su isseoyo</td><td>I can read</td></tr> <tr><td>운전하다 (to drive)</td><td>운전할 수 있어요</td><td>unjeonhal su isseoyo</td><td>I can drive</td></tr> <tr><td>수영하다 (to swim)</td><td>수영할 수 있어요</td><td>suyeonghal su isseoyo</td><td>I can swim</td></tr> </table> <p>One of my proudest moments in Seoul: when a taxi driver asked "한국어 할 수 있어요?" and I replied "네, 조금 할 수 있어요" (yes, a little). His surprised look was priceless — a Frenchman speaking Korean isn't exactly common!</p> <h2>Inability: -(으)ㄹ 수 없다 — "Cannot"</h2> <p>Simply replace 있다 (to exist / to have) with <strong>없다</strong> (to not exist / to not have):</p> <table> <tr><th>Ability</th><th>Inability</th><th>Translation</th></tr> <tr><td>갈 수 있어요</td><td>갈 수 없어요</td><td>I can't go</td></tr> <tr><td>먹을 수 있어요</td><td>먹을 수 없어요</td><td>I can't eat</td></tr> <tr><td>할 수 있어요</td><td>할 수 없어요</td><td>I can't do</td></tr> <tr><td>읽을 수 있어요</td><td>읽을 수 없어요</td><td>I can't read</td></tr> </table> <p>Elegant, isn't it? Just one word changes: 있다 → 없다. Korean can be remarkably logical when it wants to be.</p> <h2>The Short Form: 못 — For Quick Conversations</h2> <p>In everyday conversation, Koreans often use the short form <strong>못</strong> (mot) instead of -(으)ㄹ 수 없다. It's faster and more natural in spoken Korean.</p> <table> <tr><th>Long form (formal)</th><th>Short form (spoken)</th><th>Translation</th></tr> <tr><td>갈 수 없어요</td><td>못 가요</td><td>I can't go</td></tr> <tr><td>먹을 수 없어요</td><td>못 먹어요</td><td>I can't eat</td></tr> <tr><td>할 수 없어요</td><td>못 해요</td><td>I can't do it</td></tr> </table> <p>Both are correct. The long form is more polite and formal; 못 is more common in spoken language between friends or in casual settings. At the office, I use -(으)ㄹ 수 없어요. At BBQ with friends, it's 못.</p> <h3>못 with 하다 Verbs</h3> <p>Reminder: with compound 하다 verbs, separate the noun from the verb:</p> <ul> <li>운동 못 해요 (undong mot haeyo) — I can't exercise</li> <li>공부 못 해요 (gongbu mot haeyo) — I can't study</li> <li>요리 못 해요 (yori mot haeyo) — I can't cook</li> </ul> <h2>Ability vs Permission — An Important Nuance</h2> <p>In English, "can" covers both ability (I can swim) and permission (I can swim here). It's the same in Korean with -(으)ㄹ 수 있다, but context is crucial.</p> <table> <tr><th>Sentence</th><th>Ability meaning</th><th>Permission meaning</th></tr> <tr><td>여기서 수영할 수 있어요</td><td>I know how to swim here</td><td>Swimming is allowed here</td></tr> <tr><td>사진을 찍을 수 있어요</td><td>I know how to take photos</td><td>Taking photos is allowed</td></tr> </table> <p>To clarify <strong>permission</strong> specifically, use:</p> <ul> <li><strong>-아/어도 되다</strong> (-ado doeda) — To be allowed to</li> <li>여기서 사진을 찍어도 돼요? (yeogiseo sajineul jjigeodo dwaeyo?) — May I take photos here?</li> <li>들어가도 돼요? (deureogado dwaeyo?) — May I come in?</li> </ul> <p>Anecdote: at [경복궁](/en/dictionary/%EA%B2%BD%EB%B3%B5%EA%B6%81) (Gyeongbokgung) palace, I asked "사진 찍을 수 있어요?" and the guide hesitated — he wasn't sure if I was asking whether I was physically capable or whether it was allowed. Since then, I always say "찍어도 돼요?" for permission. Clarity is courtesy.</p> <h2>Prohibition: -(으)면 안 되다</h2> <p>To express "you must not" or "it's forbidden":</p> <table> <tr><th>Expression</th><th>Example</th><th>Translation</th></tr> <tr><td>-(으)면 안 되다</td><td>여기서 담배를 피우면 안 돼요</td><td>Smoking is not allowed here</td></tr> <tr><td></td><td>큰 소리로 말하면 안 돼요</td><td>You must not speak loudly</td></tr> <tr><td></td><td>늦으면 안 돼요</td><td>You must not be late</td></tr> </table> <h2>Useful Questions with "Can"</h2> <p>Here are the most useful everyday questions:</p> <ul> <li><strong>한국어 할 수 있어요?</strong> — Can you speak Korean?</li> <li><strong>매운 음식 먹을 수 있어요?</strong> — Can you eat spicy food?</li> <li><strong>내일 올 수 있어요?</strong> — Can you come tomorrow?</li> <li><strong>도와줄 수 있어요?</strong> — Can you help me?</li> <li><strong>카드로 결제할 수 있어요?</strong> — Can I pay by card?</li> </ul> <p>That last question, "카드로 결제할 수 있어요?", I still ask today at Seoul's traditional markets. Even after twelve years, some 아저씨 (ajussi — older men) at the markets only accept cash.</p> <h2>잘하다 and 못하다 — Being Good/Bad at Something</h2> <p>To express skill level, use:</p> <table> <tr><th>Expression</th><th>Meaning</th><th>Example</th><th>Translation</th></tr> <tr><td>잘하다 (jalhada)</td><td>To be good at</td><td>노래를 잘해요</td><td>He/she sings well</td></tr> <tr><td>못하다 (motada)</td><td>To be bad at</td><td>요리를 못해요</td><td>I cook badly</td></tr> <tr><td>잘 못하다</td><td>To not do very well</td><td>한국어를 잘 못해요</td><td>I don't speak Korean very well</td></tr> </table> <p>The form 잘 못해요 (jal motaeyo — I don't do it very well) is a humble and polite way to downplay your skills. Koreans use it constantly out of modesty, even when they're highly skilled. After twelve years, I've adopted this habit — when someone compliments my Korean, I automatically respond "아직 잘 못해요" (I don't speak well yet), even though my friends say that's not true.</p> <h2>Summary</h2> <table> <tr><th>Expression</th><th>Usage</th><th>Register</th></tr> <tr><td>-(으)ㄹ 수 있다</td><td>Can / know how to</td><td>All registers</td></tr> <tr><td>-(으)ㄹ 수 없다</td><td>Cannot</td><td>Formal / written</td></tr> <tr><td>못 + verb</td><td>Cannot (short)</td><td>Spoken / daily</td></tr> <tr><td>-아/어도 되다</td><td>Have permission to</td><td>Polite questions</td></tr> <tr><td>-(으)면 안 되다</td><td>Prohibition</td><td>All registers</td></tr> </table> <p>Want to test your Korean abilities? <a href="/en/signup">Join Seonsaengnim</a> and practice with interactive exercises tailored to your level.</p>