Learn Hardcore Korean: daebubun haksaengdeuri ojeone doseogwaneseo gongbuhaeyo. - Most students study at the library in the morning.

대부분 means most or the majority. It can behave like a noun or adverbial. In 대부분 학생들이, it works like a determiner-like noun modifying 학생들 to give most students. It can also stand alone as a topic (대부분은) meaning for the most part.

Is 대부분 학생들이 correct, or must it be 대부분의 학생들이?

Both are acceptable. 대부분의 학생들이 is the textbook form with 의. In everyday Korean, 의 after quantifiers like 대부분 is often dropped, so 대부분 학생들이 is common and natural.

Could I say 학생들 대부분이 instead? Any nuance difference?

Yes: 학생들 대부분이 오전에… is very natural, especially when you mean most of the specific students already in context. 대부분(의) 학생들이 can feel more generic (most students in general).

Do I need the plural marker 들 after 학생?

들 is optional. 대부분(의) 학생이 is grammatical and can still refer to many students, but most speakers include 들 here for clarity: 대부분의 학생들이.

Why is 이/가 used instead of 은/는 on 학생들?

이/가 marks the subject neutrally. 은/는 makes it a topic: 대부분의 학생들은… sets up contrast or background (as for most students, …), often implying something different for others.

Why is 에서 used with 도서관? Could I use 에?

Use 에서 for the place where an action occurs. 도서관에서 공부해요 = study at/in the library. 도서관에 공부해요 is ungrammatical; 에 with places marks location/existence or direction (e.g., 도서관에 있어요, 도서관에 가요).

Can I change the order of 오전에 and 도서관에서?

Yes. Default and most natural is time → place: 오전에 도서관에서. 도서관에서 오전에 is also grammatical and may slightly foreground the place first.

What is the difference between 오전에 and 아침에?

Both mean in the morning, but nuance differs. 오전 is the AM time before noon, more neutral/formal. 아침 is the morning period around waking/breakfast and can feel earlier/more everyday. They overlap a lot.

Can I drop the 에 after 오전?

Often yes in casual speech. 오전(에) 도서관에서 공부해요 is heard without 에 when the time is obvious. Keeping 에 is always safe and slightly more formal.

Does 공부해요 mean they are doing it right now or as a habit?

Korean simple present covers both. Here, with 대부분 and 오전에, it reads as a habitual statement. For a current action, use 공부하고 있어요.

How does 공부해요 compare with 공부합니다 and 공부해?

All mean study, differing in politeness. 공부해요 = polite informal. 공부합니다 = polite formal (speeches, news). 공부해 = casual to friends/younger people.

What is the difference between 공부하다 and 배우다?

공부하다 = to study (the act of studying, often self-directed). 배우다 = to learn (receive instruction). Example: 한국어를 공부해요 vs 한국어를 배워요.

Can I say 공부를 해요 with an object marker?

Yes: 공부를 해요 is fine and can lightly emphasize the act. If you name the subject matter, use an object: 한국어를 공부해요. Otherwise 공부해요 without 를 is most common.

Is 대부분은 possible here?

Yes, but only when the group is already clear from context. You’d say 대부분은 오전에 도서관에서 공부해요 (as for most [of them]…). If you want to name the group in the same clause, prefer 학생들 대부분은 … or 대부분의 학생들은 …, not 대부분은 학생들이 ….

What happens if I move 대부분 after the place/time, like 학생들이 오전에 도서관에서 대부분 공부해요?

Then 대부분 modifies the action: they mostly study (rather than do other things) in that setting. 대부분 학생들이… modifies the subject, meaning most students.

Any pronunciation tips for the whole sentence?

Tensification: 학생 sounds like [학쌩] (hak-ssaeng). A simple romanization for the whole sentence is: dae-bu-bun hak-ssaeng-deu-ri o-jeon-e do-seo-gwan-e-seo gong-bu-hae-yo.

Is 도서관 the same as 서점?

No. 도서관 = library (borrow/read). 서점/책방 = bookstore (buy). A school reading room is 열람실.

Can I make the time phrase contrastive, like only in the morning?

Add 는/은 to the time: 오전에는 도서관에서 공부해요 implies contrast (e.g., afternoons are different). You can state the contrast later.

Is 학생들께서 appropriate instead of 학생들이?

Generally no. 께서 is the honorific subject marker for respected people (elders, customers, professors). 학생들께서 is unusual unless you’re being overtly deferential to students; 학생들이 is normal.

Any spacing rules I should notice?

Postpositions attach with no space: 오전에, 도서관에서. Keep a space after 대부분 when it modifies a noun: 대부분 학생들, or use 의 as 대부분의 학생들. Avoid writing them as one block like 대부분학생들.