Learn Hardcore Korean: geuneun jibeseo gongbuhaneun pyeonijiman doseogwanppunman anira kapeeseodo jaju gongbuhae. - He tends to study at home, but he often studies not only at the library but also at cafés.

With action verbs: habitual tendency. Ex) 저는 집에 있는 편이에요 = I tend to stay home.
With adjectives: degree. Ex) 가격이 비싼 편이에요 = It’s on the expensive side. So 집에서 공부하는 편 ≈ “(he) tends to study at home.”

Why is it 편이지만 here? Could I use 하지만 instead?

-지만 attaches directly to nouns/adjectival predicates (here, 편 with 이다) to mean “but.”
A two-sentence alternative uses the sentence adverb 하지만:
- 그는 집에서 공부하는 편이야. 하지만 도서관뿐만 아니라 카페에서도 자주 공부해. Both are fine; -지만 makes one smooth complex sentence.

Is starting with 그는 natural? Should I drop it or use something else?

In everyday Korean you usually drop pronouns or use a name/title:

(그는) → often omitted: 집에서 공부하는 편이지만 …
Use a name/title: 민수는 …, 오빠는 … 그는 is fine in writing or when you need to contrast “he” with someone else. Using 그녀 for “she” is rare in conversation.

How does 뿐만 아니라 work? What’s the basic pattern?

The core pattern is “Not only A but also B”:

Noun pattern: A + 뿐만 아니라 B + 도
- 도서관뿐만 아니라 카페에서도 (B takes 도)
Verb/clausal pattern: V-(으)ㄹ 뿐만 아니라 …
- 공부할 뿐만 아니라 일을 해요 = He not only studies but also works.

Should it be 도서관에서뿐만 아니라 instead of 도서관뿐만 아니라?

For parallel, especially in careful writing, many prefer:

도서관에서뿐만 아니라 카페에서도 … In speech, 도서관뿐만 아니라 카페에서도 is common and understood. The more “textbook-parallel” version puts 에서 on both items.

What exactly is 에서도?

It’s the location particle 에서 plus the additive 도. The rule: add 도 after case particles/postpositions.

에 + 도 → 에도
에서 + 도 → 에서도
에게 + 도 → 에게도
로 + 도 → 로도

Why is it 공부하는 first but 공부해 at the end? Is that a tense mismatch?

No. -는 in 공부하는 편 is the present/habitual adnominal that turns the verb into a modifier for the noun 편 (“the kind that studies…”). The final 공부해 is the main predicate of the sentence in the casual present.

Could I say 공부하는 편인데 instead of 편이지만?

Yes, with nuance differences:

편이지만 = clear, explicit contrast “although/ but.”
편인데 = softer, backgrounding info that leads into the next point (“he’s the type who studies at home, and (given that) …”). In casual speech -는데 often sounds more natural.

What speech level is 공부해? Can I use 공부해요 or 공부합니다?

공부해: intimate casual (to friends/younger people).
공부해요: polite informal, safest default with most people.
공부합니다: formal polite (announcements, news, formal writing). Choose based on your audience.

Where should I put 자주?

Default position is right before the verb phrase:

카페에서도 자주 공부해 (given) is perfect.
You can also say: 도서관에서도 자주 공부해. Avoid: 자주 카페에서도 공부해 (sounds awkward); adverbs rarely precede location phrases like that.

Can I use 말고도 instead of 뿐만 아니라?

Yes, with a slightly different feel:

도서관 말고도 카페에서(도) 자주 공부해. = “Besides the library, he also studies at cafes.” 말고도 is a bit more casual and simpler structurally. 뿐만 아니라 sounds a little more formal/emphatic “not only A but also B.”

Can I drop the second 공부 and just say … 카페에서도 자주 해?

Not by itself. 하다 needs a clear antecedent. You could say:

… 카페에서도 자주 하기도 해. (uses 하- pro-verb with -기도 to mean “does (that) too.”) But the natural, straightforward way is to repeat 공부해.

Is there any difference between 뿐만 아니라 and 뿐만이 아니라?

Both are used and understood as “not only … but also ….” Many style guides treat 뿐만이 아니다 as the full form, but in practice 뿐만 아니라 is extremely common. With other particles attached, you usually see:

도서관에서뿐만 아니라 카페에서도 … (You may also encounter 도서관에서뿐만이 아니라, but the version without 이 is very common and reads cleaner.)