Learn Hardcore Korean: ibeon hakgie doseogwaneseo gongbuhaeyo.

이번 means this, 학기 means semester. Together, 이번 학기 = this semester. The particle -에 marks when an action happens, so 이번 학기에 means during this semester (i.e., in this semester).

Why is 도서관에서 used instead of 도서관에?

The particle -에서 marks the location where an action takes place. 도서관에서 공부해요 means I study at the library. If you used 도서관에, it would suggest going to the library or simply being there, not performing the action of studying.

Why doesn’t 공부해요 have an object marker like 공부를 해요?

The verb 공부하다 (to study) already combines the noun 공부 with 하다, so adding -를 is optional. Koreans often drop -를 here for brevity: 공부해요 alone means study. Saying 공부를 해요 makes the object explicit but doesn’t change the meaning.

How do you form 공부해요 from 공부하다?

공부하다 is 공부 (study) + 하다 (to do). To make it polite present tense, you replace -하다 with -해요:
공부 + 해요 → 공부해요.

Where is the subject in this sentence?

Korean often omits the subject when it’s clear. Here, it’s (저는) I who is studying. You could say 저는 이번 학기에 도서관에서 공부해요, but since context clarifies the subject, it’s left out.

Is the word order always time–place–subject–verb?

The most common order is time–place–subject–verb, and the verb must come last. You can move time and place for emphasis, but particles tell you each part’s role, so meaning stays clear.

Can we make this sentence more formal?

Yes. In formal polite style use -습니다 instead of -해요:
이번 학기에 도서관에서 공부합니다.

Does 공부해요 indicate a one-time action or a habitual action?

Korean present tense can express both. In this context, 이번 학기에 도서관에서 공부해요 usually implies a habitual or regular action throughout the semester. Context will tell you if it’s a one-off session or an ongoing habit.