Learn Hardcore Korean: haksaengdeuri jilmuneul haeyo.

The suffix 들 is a plural marker. Adding it to 학생 turns “student” into “students.” It’s not strictly mandatory—if context already shows you’re talking about more than one student, you can drop 들. But including it makes the plurality explicit.

Why is the subject marked with 이 in 학생들이? When do I use 이 vs. 가?

In Korean, 이/가 mark the grammatical subject. You attach 이 after a noun ending in a consonant and 가 after a noun ending in a vowel. Since 학생들 ends in the consonant ㄹ, you add 이 to get 학생들이.

Why does 질문 take 을 in 질문을 해요? What’s the function of 을?

을/를 are object markers. They show what the verb directly acts upon. You use 을 after a consonant and 를 after a vowel. Here, 질문 ends with ㄴ, so it takes 을, indicating that “questions” are the direct object of “ask.”

What exactly is 해요 in 질문을 해요, and how does it relate to 하다?

해요 is the polite present-tense form of the verb 하다 (“to do”). The stem 하 plus -아요 would be 하아요, but it contracts to 해요. This speech level is called 해요체, the friendly/polite style you use in everyday conversations with people you’re not super formal with.

Why does the verb 해요 come at the end? Is that always the case in Korean?

Korean generally follows a Subject-Object-Verb (SOV) word order, so the verb almost always appears at the end of the sentence. Here, 학생들이 (subject) + 질문을 (object) + 해요 (verb).

Can I drop 학생들이 if it’s obvious who’s doing the asking?

Yes. Korean often omits subjects when they’re clear from context. If everyone knows you’re talking about the students, you can simply say 질문을 해요 (“They ask questions”).

How does 질문 (a noun) become a verb in 질문을 해요?

질문 is a Sino-Korean noun meaning “question.” By attaching 하다 (“to do”) to a noun, you turn it into a verb. So 질문하다 literally means “to do a question,” i.e. “to ask a question.” You then conjugate 하다 as usual.

What’s the difference between 질문하다 and the native Korean verb 묻다 for “ask”?

Both mean “to ask,” but 질문하다 is a Sino-Korean construction and feels more formal or neutral, often used in writing or presentations. 묻다 is the native Korean verb and is common in everyday speech.

Could I use the more formal 합니다 instead of 해요? What would 학생들이 질문을 합니다 imply?

Yes. 합니다 is the formal polite style (합니다체). Using 학생들이 질문을 합니다 sounds more official—appropriate for reports, lectures, or when you need to be very polite.