Learn Hardcore Korean: gwairi mure tteoyo. - The fruit floats in water.

이/가 are subject markers; they flag 과일 as the subject of the sentence (“the thing doing or being something”). 을/를 mark objects (what receives an action). Since 과일 is “floating” (it’s the subject doing the floating), we use 이.

What does the particle 에 indicate in 물에?

Here 에 marks a static location (“in/at”). 물에 means “in the water.” It answers “where?” rather than “to where?” (which would use the same 에 but imply movement, e.g. “go into the water”).

Why is the verb written 떠요 instead of 뜨어요?

뜨다 is an “ㅡ”-irregular verb. When adding a vowel suffix like -어요, you drop the stem vowel ㅡ and replace it with ㅓ.
• 뜨다 → 뜨 + 어요 → drop ㅡ → 떠요

What is the difference between 떠요 and 떠 있어요?

• 떠요 is simple present; it describes a present state or habitual action (“floats”).
• 떠 있어요 uses the progressive/stative construction -아/어 있다, emphasizing “is in the state of floating right now.” In many contexts they’re interchangeable, but 떠 있어요 more strongly highlights “ongoing state.”

Could I say 과일은 물에 떠요 instead of 과일이 물에 떠요?

Yes. 은/는 is the topic marker and gives a general or contrastive tone (“As for fruit, it floats in water”). 이/가 is more neutral for simply stating “the fruit floats.” Both are grammatical, but nuance differs:
• 과일이 물에 떠요 = “(Here’s a fact) the fruit floats in water.”
• 과일은 물에 떠요 = “Speaking of fruit, it floats in water (unlike something else).”

Why not say 물 위에 떠요 (“on top of the water”)?

You can say 물 위에 떠요 if you want to specify “floating on the surface of the water.”
• 물에 떠요 = “in the water (somewhere in it, but we know it floats).”
• 물 위에 떠요 = “on the surface of the water.”

Can you drop the subject or particles and say 과일 물에 떠요?

Korean often drops subjects if context is clear (so you could say 물에 떠요 when it’s obvious you mean fruit). However, dropping the location particle (물에) would make it ungrammatical or confusing. Particles clarify roles, so omitting them entirely is not recommended.

How do you change 과일이 물에 떠요 to past tense?

Attach the past suffix -었어요 (and apply the same ㅡ-irregular rule):
• 뜨다 → stem 뜨 + 었어요 → drop ㅡ → 떴어요
Sentence: 과일이 물에 떴어요. (“The fruit floated in the water.”)

How would you make the sentence more formal or polite?

Use the formal declarative ending -습니다:
• 뜨다 → 뜨 + 습니다 (keeping the ㅡ-irregular drop) → 뜹니다
Formal sentence: 과일이 물에 뜹니다.