Learn Hardcore Korean: geureonde eotteon daneoreul meonjeo oewoya halji moreugesseoyo. - But I don’t know which word I should memorize first.

그런데 is a conjunction that can mean but, however, or by the way. It signals a shift in thought or introduces a related question or comment.

What does 어떤 단어 mean, and why use 어떤 instead of 무슨?

어떤 means which or what kind of, so 어떤 단어 is which word. 무슨 단어 also means what word, but 어떤 often implies selecting from a set of known options, while 무슨 is more general.

Why does 단어 take the particle 를?

를 (or 을 after a consonant) is the direct object marker in Korean. It tells us that 단어 is the thing being acted upon by the verb 외우다 (to memorize).

What is the role of 먼저 in this sentence?

먼저 is an adverb meaning first or before anything else. It indicates the order of actions, so the speaker is unsure about which word to memorize first.

Can you break down the grammar of 외워야 할지 모르겠어요 and explain how it expresses I don’t know which word to memorize first?

This phrase combines three parts:

외우다 → stem 외우- (to memorize)
-어야 하다 attaches: 외우 + 어야 하다 → 외워야 하다 (must memorize)
-ㄹ지 모르겠다 uses the attributive form: 외워야 하다 → 외워야 할지 모르겠다 (don’t know whether one must memorize)
Adding -어요 yields 외워야 할지 모르겠어요, literally I don’t know whether I must memorize, but in context I don’t know which word I should memorize first.

Why is it 외워야 and not 외우어야?

Because of vowel contraction. 외우 + 어야 becomes 외우어야, but standard Korean contracts 우 + 어 → 워, so 외우어야 simplifies to 외워야.

Why is the subject (e.g., 저) omitted in the sentence?

In Korean, subjects are often dropped when they’re clear from context. Here, it’s obvious the speaker is talking about themselves, so adding 저 (I) isn’t necessary.

What politeness level is 모르겠어요, and when would you use it?

모르겠어요 is in the polite casual style (해요체). It’s suitable for everyday conversations with people you’re not very close to (classmates, coworkers, strangers) or when you want to show basic respect.