seonsaengnimi eoryeoun bubuneul jasehi seolmyeonghae jusyeosseoyo.

이 is the subject marker here, so 선생님이 means the teacher as the person doing the action.

In this sentence, the teacher is the one who explained, so 선생님이 marks the doer of the verb.

• 선생님이 = the teacher (subject)
• 설명해 주셨어요 = explained (for someone)

You could also sometimes hear 선생님께서, which is a more honorific way to mark the subject when talking about someone respected.

Both 을 particles mark objects, but they belong to different parts of the sentence structure.

1. 어려운 부분을

   • 부분 = part
   • 어려운 부분 = difficult part
   • This is the thing being explained.

2. The verb phrase is 설명해 주셨어요, and 어려운 부분을 is its object.

So the main object of the sentence is:

• 어려운 부분을 = the difficult part

There is only one object phrase here; it just happens to include the object marker 을 after 부분.

어려운 is the form used when 어렵다 modifies a noun.

• 어렵다 = to be difficult
• 어려운 = difficult (used before a noun)

So:

• 어려운 부분 = a difficult part

This is similar to English turning a descriptive idea into something that directly modifies a noun.

Examples:

• 큰 집 = a big house
• 재미있는 영화 = an interesting movie
• 어려운 부분 = a difficult part

So 어려운 is not the dictionary form; it is the noun-modifying form.

부분 means part, section, or portion.

In this sentence, 어려운 부분 means:

• the difficult part
• the part that is difficult

This could refer to a part of:

• a lesson
• a text
• a problem
• an explanation
• homework

It is a very common word in Korean.

자세히 is an adverb meaning in detail or carefully/thoroughly.

It describes how the teacher explained.

• 자세히 설명해 주셨어요 = explained in detail

It comes from 자세하다 (to be detailed), and the adverb form is 자세히.

Compare:

• 자세한 설명 = a detailed explanation
• 자세히 설명하다 = to explain in detail

Yes. This is a very useful Korean verb pattern.

Breakdown

• 설명하다 = to explain
• 설명해 = explain and...
• 주다 = to give
• -아/어 주다 = to do something for someone
• 주시다 = honorific form of 주다
• 주셨어요 = gave/did for someone, with honorific and past polite ending

So:

• 설명해 주셨어요 literally means something like
  gave the favor of explaining
• Natural English: explained it for me/us or simply explained it

This pattern often adds the nuance that the action was done for the benefit of the speaker or someone else.

Great question. Both are possible, but the nuance is different.

설명하셨어요

This simply means:

• explained

설명해 주셨어요

This means:

• explained for me/us
• kindly explained
• did the favor of explaining

So -아/어 주다 adds a sense of benefit or kindness. It often sounds warmer and more natural when someone did something helpful for you.

In this sentence, 주셨어요 suggests:

• the teacher explained it for the student’s benefit
• the speaker feels some appreciation or helpfulness

The honorific part is -시-, inside 주셨어요.

Breakdown

• 주다 = to give
• 주시다 = honorific form
• 주셨어요 = honorific + past + polite

This is used because the subject is 선생님 (teacher), someone deserving respect.

So the sentence is respectful toward the teacher.

Yes. 주셨어요 is past tense.

The ending -었- marks the past:

• 주세요 = give / do for someone
• 주셨어요 = gave / did for someone

So the sentence means that the teacher explained it already.

-어요 is a polite speech ending. It is commonly used in everyday respectful conversation.

So 주셨어요 is:

• polite
• not casual
• not the highest formal style either

This style is appropriate in many normal situations, especially when speaking politely.

Compare:

• 주셨어요 = polite everyday style
• 주셨습니다 = more formal
• 주셨어 = casual/non-polite

Usually, the beneficiary is the speaker or a group including the speaker, such as me, us, or sometimes the listener depending on context.

So this sentence often implies something like:

• The teacher explained the difficult part for me/us in detail.

Korean often leaves that person unstated if it is obvious from context.

Both can be possible, but they do slightly different jobs.

선생님이

This focuses on the subject as the one who did the action:

• The teacher explained...

선생님은

This would make teacher the topic:

• As for the teacher, he/she explained...

Using 이/가 is very natural when simply presenting who performed the action.
Using 은/는 would add more of a topic or contrast nuance.

For example:

• 선생님이 어려운 부분을 자세히 설명해 주셨어요.
  = The teacher explained the difficult part in detail.
• 선생님은 어려운 부분을 자세히 설명해 주셨어요.
  = As for the teacher, he/she explained the difficult part in detail.
  (maybe contrasting with someone else)

Yes. Korean word order is flexible as long as the meaning stays clear.

These are all possible:

• 선생님이 어려운 부분을 자세히 설명해 주셨어요.
• 선생님이 자세히 어려운 부분을 설명해 주셨어요.
• 어려운 부분을 선생님이 자세히 설명해 주셨어요.

The most neutral and natural version here is the original:

• 선생님이 어려운 부분을 자세히 설명해 주셨어요.

Korean often places adverbs like 자세히 before the verb phrase.

설명해 is the contracted conversational form of 설명하여.

• 설명하다
  • -아/어 → 설명하여
• In normal speech, 설명하여 becomes 설명해

This contraction is extremely common in everyday Korean.

So:

• 설명하여 주셨어요 = more written/stiff
• 설명해 주셨어요 = natural spoken Korean

Yes, a little.

Because of -아/어 주시다, the sentence can sound like the speaker is acknowledging that the teacher kindly did something helpful.

So compared with a plain factual sentence, this version may carry a mild feeling of:

• gratitude
• appreciation
• respect

That does not mean it is overly emotional; it is just a natural, polite, and considerate way to say it.

A casual version could be:

• 선생님이 어려운 부분을 자세히 설명해 주셨어.

If you remove the honorific too, it becomes less respectful and would usually not be appropriate for a teacher:

• 선생님이 어려운 부분을 자세히 설명해 줬어.

And a very plain version without the for someone nuance would be:

• 선생님이 어려운 부분을 자세히 설명했어.

For a teacher, the original 설명해 주셨어요 is much more appropriate and natural.