-아/어야

Must or Only if

Let's study about Korean grammar "-아/어야" today. This grammar point is used to express necessity, obligation, or condition that must be fulfilled. It’s commonly translated as "must" or "only if" in English, and it often emphasizes a requirement for a certain action or state.

---

Definition:

"-아/어야" is attached to the stem of a verb or adjective to indicate that something must happen or a condition must be met for the following action or result to occur.

---

Usage:

1. To express necessity or obligation:

   • It shows that the preceding action or state is necessary for the situation in the second clause.

   • Often translates to "must" or "have to."

2. To express a necessary condition:

   • It is used when the first clause is a prerequisite for the second clause.

   • Often translates to "only if."

3. To emphasize importance or priority:

   • Indicates that something is critically important for a subsequent result.

---

Considerations for Use:

1. The verb conjugation "-아/어야" depends on the verb stem:

   • If the verb stem ends in ㅏ or ㅗ, use -아야.
     Example: 가다 → 가야

   • For other vowel endings, use -어야.
     Example: 먹다 → 먹어야

   • For 하다 verbs, use -해야.
     Example: 공부하다 → 공부해야

2. This structure is often followed by verbs like 하다, 되다, or phrases indicating conditions.

---

Examples:

1. Necessity or Obligation:

• 문제를 풀어야 합격할 수 있어요.
  (You must solve the problems to pass.)

• 건강을 유지하려면 운동을 해야 해요.
  (You have to exercise to stay healthy.)

2. Necessary Condition:

• 시간이 있어야 여행을 갈 수 있어요.
  (You can go on a trip only if you have time.)

• 한국어를 잘 배워야 통역사가 될 수 있어요.
  (Only if you learn Korean well, you can become an interpreter.)

3. Emphasizing Importance:

• 친구와의 약속을 지켜야 관계가 좋아질 거예요.
  (You must keep promises with your friends to improve the relationship.)

• 열심히 연습해야 대회에서 이길 수 있어요.
  (You must practice hard to win the competition.)

---

Similar Grammar Structures:

1. "-아/어야지": A colloquial form that also implies obligation but can be slightly less formal.

   • Example: 일찍 자야지 내일 일찍 일어날 수 있어요. (You should go to bed early to wake up early tomorrow.)

2. "-고 나서야": Indicates that something happens only after a specific action.

   • Example: 설거지를 하고 나서야 쉴 수 있어요. (I can only rest after doing the dishes.)

3. "-지 않아도": Indicates that something is not necessary.

   • Example: 빨리 가지 않아도 돼요. (You don’t have to go quickly.)

---