jungyohan memoreul byeoge butyeo dueosseoyo.

붙여 두었어요 uses the pattern -아/어 두다.

• 붙이다 = to stick, attach
• 붙여 두다 = to stick something somewhere and leave it that way

So 두다 adds the idea that the action was done and the result was kept in place. In this sentence, it is not just that the memo was attached once; it was attached and left on the wall for later use, reference, or convenience.

In past polite form:

• 붙여 두었어요 = attached it and left it there

붙였어요 simply says the action happened:

• 메모를 벽에 붙였어요 = I stuck the memo on the wall

붙여 두었어요 adds extra nuance:

• it was done intentionally
• it remains that way
• often it was done for later convenience or because it should stay there

So the difference is small in English, but in Korean it is very natural and meaningful.

Because 두다 here is an auxiliary verb, and in standard spacing it is usually written separately from the main verb.

So:

• 붙여 두었어요 is the standard spacing

This is similar to other patterns such as:

• 읽어 보다
• 써 두다
• 열어 놓다

Even though they are closely connected in meaning, Korean usually writes them as separate words.

에 marks the location or target where something is placed or attached.

Here:

• 메모를 = the memo is the thing being attached
• 벽에 = the wall is the place it is attached to

So 벽에 붙이다 means to attach something to the wall.

This is why 에 is used, not 를.

Because 중요하다 has to change form before a noun.

When a descriptive verb such as 중요하다 modifies a noun, it becomes 중요한.

So:

• 중요하다 = to be important
• 중요한 메모 = an important memo

This is the normal noun-modifying form for many -하다 descriptive verbs:

• 조용하다 → 조용한 방
• 이상하다 → 이상한 사람

를 is the object marker. It marks 메모 as the direct object of 붙이다.

In other words, the memo is the thing receiving the action.

So in this sentence:

• 메모를 = the thing being stuck up
• 벽에 = the place it is stuck to

Yes. Korean very often leaves out the subject when it is understood from context.

So this sentence does not explicitly say I, we, or someone. Depending on context, it could mean:

• I attached it
• we attached it
• someone attached it

In many learning materials, it gets translated with I because that is the most natural default in isolation, but the Korean sentence itself does not force that subject.

-어요 is the standard polite speech level.

So 붙여 두었어요 is polite and natural in everyday conversation.

Compare:

• 붙여 두었어요 = polite standard
• 붙여 두었습니다 = more formal
• 붙여 뒀어 = casual, plain conversation

Yes. Very often, 두었어요 contracts to 뒀어요.

So:

• 붙여 두었어요
• 붙여 뒀어요

Both are natural and mean the same thing. The contracted form is very common in speech and informal writing.

This is an important verb pair.

• 붙이다 = to attach something, to stick something on
  
  • transitive
• 붙다 = to stick, to be attached
  
  • intransitive

Examples:

• 메모를 벽에 붙였어요
  I attached the memo to the wall.

• 메모가 벽에 붙어 있어요
  The memo is attached to the wall.

So in your sentence, 붙이다 is used because someone actively attached the memo.

Yes. Korean word order is flexible because particles show each word’s role.

So these are both natural:

• 중요한 메모를 벽에 붙여 두었어요
• 벽에 중요한 메모를 붙여 두었어요

The verb usually stays at the end, but the order of the other parts can shift for emphasis, rhythm, or context.

Although it is written 붙여, it is commonly pronounced closer to 부쳐.

That is because 붙이다 is pronounced like 부치다, and the conjugated form follows that pronunciation pattern.

So the whole phrase is often heard roughly as:

• 부쳐 두었어요
• or in contracted speech, 부쳐 뒀어요

The spelling stays 붙여, but the pronunciation is different.

Yes. 메모 is a very common loanword in Korean and sounds perfectly natural in everyday speech.

Depending on context, you might also see words like:

• 쪽지 = note, slip of paper
• 메모지 = memo paper

But 메모 itself is extremely common and normal here.