～ことができる (koto ga dekiru) - Expressing Ability and Possibility

Japanese verbs are great, but they can't always stand alone. To use dekiru (to be able to), you need a noun. But what if your "ability" is an action? You cannot just stick a verb next to dekiru. You need a bridge. That bridge is the word koto. In Japanese, koto turns an action into a "thing." It is like adding "-ing" or "the act of" in English. When you say taberu koto, you are saying "the act of eating." By adding ga dekiru, you are literally saying "The act of eating is possible." It sounds a bit robotic when translated literally. However, in Japanese, it is perfectly natural. It is like a grammar traffic light. It tells the listener exactly what you are capable of doing.

1. 1Building this phrase is as simple as making instant ramen. Just follow these three steps:
2. 2Take any verb you want to use.
3. 3Change that verb into its Dictionary Form (the plain form found in dictionaries).
4. 4Add koto ga dekiru (～ことができる) right after it.
5. 5Here are a few quick examples:
6. 6taberu (to eat) + koto ga dekiru = taberu koto ga dekiru (can eat)
7. 7iku (to go) + koto ga dekiru = iku koto ga dekiru (can go)
8. 8hanasu (to speak) + koto ga dekiru = hanasu koto ga dekiru (can speak)
9. 9Yes, even irregular verbs like suru and kuru follow this rule. No weird conjugation changes here! Just use suru koto ga dekiru or kuru koto ga dekiru. It is very reliable.

You will use this pattern in three main real-world scenarios. First, use it for acquired skills. If you spent years learning the piano, say piano o hiku koto ga dekiru. Second, use it for situational possibility. Imagine you are at a museum. You want to know if you can take photos. You would ask if you shashin o toru koto ga dekiru. Third, use it for physical abilities. If you can run five miles, this is your phrase. It is great for job interviews when listing your strengths. It is also perfect for asking about rules in a new country. "Can I park here?" or "Can I use Wi-Fi?" are perfect fits for this grammar.

Don't use this for every single "can" in English. If you are asking for permission in a casual way, ～te mo ii desu ka is often better. For example, asking to use the bathroom. Using koto ga dekiru there sounds like you are asking if it is physically possible for you to use it. That might get you some funny looks! Also, avoid using it for things that happen naturally. You don't usually say "I can see the sun" using this grammar. There are other words like mieru for that. Think of koto ga dekiru as a conscious ability or a specific rule-based possibility. If it's a simple reflex, skip it.

The most common trip-up is forgetting the ga. Some people say koto dekiru. While people might understand you, it sounds a bit messy. Always keep that ga in there for clarity. Another mistake is using the wrong verb form. Never use the masu form before koto. Tabemasu koto is a big no-no. Always stick to the dictionary form. Also, be careful with suru verbs. For a noun like unten (driving), you can just say unten ga dekiru. You don't always need unten suru koto ga dekiru. Both are okay, but the shorter one is more common. Don't work harder than you have to!

You might have heard of the Potential Form (like taberareru). This is the shorter version of "can." So, what is the difference? ～ことができる is slightly more formal and clear. It is like the difference between saying "I am able to speak" and "I can speak." In written Japanese or formal speeches, koto ga dekiru is a superstar. In quick, casual conversation, the potential form is more common. Also, koto ga dekiru is better for complex sentences. If your verb phrase is long, adding koto ga dekiru at the end keeps it organized. It acts like a neat little bow on a package.