Learn Hardcore Korean: seorabeul yeoreoyo.

을 is the object particle that marks 서랍 (“drawer”) as the direct object of the verb. In Korean, when a noun ends in a consonant, you attach 을; if it ends in a vowel, you attach 를.

Why is the verb written as 열어요 instead of 열아 or 열아요?

The dictionary form of “to open” is 열다. To form the polite present tense, you take the stem 열- and add -어요 (because the stem vowel is ㅓ). So: 열 + 어요 → 열어요. You wouldn’t say 열아 (that’s ungrammatical) or 열아요 (that ending is used after different stem vowels).

What level of politeness is expressed by 열어요?

열어요 is the “polite informal” or simply polite present-tense form (also called the 해요체). It’s appropriate in most daily conversations with strangers, acquaintances, or anyone older than you when you want to be polite but not overly formal.

How would you say “open the drawer” in a casual (반말) style?

Drop the polite ending 요. You get 서랍을 열어. That’s suitable among very close friends or younger people.

How can I turn this into a polite request, “Please open the drawer”?

Add the helping verb 주다 in its polite form:
서랍을 열어 + 주세요 → 서랍을 열어 주세요.
You can also say 서랍을 열어 주시겠어요? for an even more courteous request.

Why is there no subject (like “I” or “you”) in this sentence?

Korean often omits subjects when they’re clear from context. Here, the implied subject could be “I,” “you,” or “he/she,” depending on the situation, but you don’t need to state it explicitly.

Is 열어요 an irregular verb?

No, 열다 is a completely regular verb. Its stem doesn’t trigger any consonant or vowel changes when you add -어요.

How do you romanize 서랍을 열어요 using the Revised Romanization system?

It’s written as seorabeul yeoleoyo. If you’re using McCune–Reischauer, it would be sŏrabŭl yŏlŏyo.