Learn Hardcore Korean: haksaengdeuri ppareuge jilmuneul haeyo.

The ending –들 makes 학생 (“student”) plural, and –이 is the subject particle (“-이/가”). Together 학생들이 means “(the) students” as the subject of the sentence. Without –들, 학생 would be singular. Without –이, you wouldn’t mark it as the subject.

What does 빠르게 mean and why not 빠른?

빠르게 is the adverb form of 빠르다 (“to be fast”). You turn adjectives/adverbs ending in -다 into adverbs by replacing -다 with -게. So 빠르다 → 빠르게 (“quickly”). 빠른 would be the attributive adjective form, used before a noun (e.g. 빠른 차 “a fast car”), not to modify a verb.

Why is there 질문을 in the sentence?

질문 means “question.” The particle –을 marks it as the direct object. So 질문을 해요 literally “do a question,” which is how Korean expresses “ask a question.”

Why do we say 질문을 해요 instead of just 묻다 (“to ask”)?

Both are possible. 묻다 is a standalone verb “to ask,” but 질문하다 (split as 질문을 하다) is a Sino-Korean compound also meaning “to ask a question.” Learners often prefer 질문하다 in neutral or polite contexts. In everyday speech, 묻다 can feel more colloquial or idiomatic depending on the situation.

What tense and level of politeness is 해요?

해요 is the present-tense, polite (also called “해요체”) form of 하다. It indicates a neutral, polite statement about what’s happening now or habitually: “(They) ask.”

Could the word order change? For example, 학생들이 질문을 빠르게 해요?

Yes. Korean word order is relatively flexible. Adverbs like 빠르게 can appear before the verb or between the object and verb. All of these are grammatical:

학생들이 빠르게 질문을 해요.
학생들이 질문을 빠르게 해요.
The emphasis slightly shifts, but the core meaning remains “Students ask questions quickly.”

Why use –이/가 (이 in 학생들이) instead of the topic marker –은/는?

–이가/가 marks the grammatical subject, introducing new or focal information. –은/는 marks the topic and can imply contrast or established context. Here, we simply state “Students (no prior topic) do this action,” so –이/가 is more natural.

Is 빠르게 the only way to say “quickly”? What about 빨리?

Both mean “quickly,” but 빨리 is a pure Korean adverb and more common in everyday speech. 빠르게 is the adverbial form of the adjective 빠르다 and slightly more formal or written. In speech, you might hear:

학생들이 빨리 질문해요.
학생들이 빠르게 질문해요.
They’re interchangeable in meaning; your choice affects register and style.