gichimi oraegamyeon geomsareul bada boneun ge johdae.

A natural breakdown is:

• 기침이 = the cough / a cough
  • subject marker 이
• 오래가면 = if it lasts a long time
• 검사를 = an examination / test / checkup
  • object marker 를
• 받아 보는 = trying getting / getting (it) done to see
• 게 = shortened form of 것이, meaning the act of... or it
• 좋대 = they say it’s good / I heard it’s good

So the sentence is saying something like:

If a cough lasts a long time, they say it’s good to get examined.

The exact English wording may vary, but that is the basic structure.

Here 이/가 marks 기침 as the subject of 오래가다.

• 기침이 오래가면 = if the cough lasts a long time

If you used 기침은, it would sound more contrastive or topic-focused, like:

• As for a cough, if it lasts a long time...

So 기침이 is the more straightforward choice when you are simply describing what happens to the cough.

It comes from:

• 오래가다 = to last a long time
• -면 = if / when

So:

• 오래가면 = if it lasts a long time

This is one of those expressions that is best learned as a chunk:

• 감기가 오래가요. = The cold lasts a long time.
• 기침이 오래가요. = The cough lasts a long time.

Even though 가다 often means to go, in 오래가다 the whole expression means to continue / last.

Because 검사 here is a noun meaning examination, test, or medical check.

In Korean, you receive an examination:

• 검사를 받다 = to undergo / receive an examination

So 검사 is the object of 받다, which is why it takes 를:

• 검사를 받다
• 건강검진을 받다
• 치료를 받다

This is different from English, where we often say get checked instead of receive an examination.

That is just the natural Korean expression.

Korean often uses 받다 (to receive) for things that are done to you or given to you, especially in formal or medical contexts:

• 검사를 받다 = get an examination
• 치료를 받다 = receive treatment
• 수업을 받다 = take/receive a class
• 도움을 받다 = receive help

So although the literal wording may feel different, 검사를 받다 is completely normal Korean.

Great question. The -아/어 보다 pattern usually adds the idea of:

• trying something
• doing something and seeing how it goes
• sometimes a softer, less forceful suggestion

So:

• 검사를 받는 게 좋대 = They say it’s good to get an examination
• 검사를 받아 보는 게 좋대 = They say it’s good to try getting an examination / to get checked out

In real English, we usually would not translate 보다 literally as try every time. Here it makes the advice sound a bit softer and more practical, like:

• It’d be good to get it checked out
• You might want to get examined

So 보다 often affects the nuance more than the direct translation.

Here 보는 게 is turning the action into something like the act of doing it.

Step by step:

• 받아 보다 = to try receiving / to get checked out
• 받아 보는 것 = the act of trying that
• 받아 보는 게 = shortened conversational form of 받아 보는 것이

Then:

• 받아 보는 게 좋다 = it is good to get checked out

So 게 here is not a separate special meaning by itself; it is just the colloquial contraction of 것이.

좋대 is a casual spoken form of 좋다고 해.

It carries a reported speech / hearsay feeling:

• 좋다고 해 = (someone) says it is good
• 좋대 = they say it’s good / I heard it’s good

So the speaker is not necessarily presenting this as their own direct opinion. It sounds more like:

• Apparently it’s good to...
• They say it’s better to...

That -대 ending is very common in conversation.

Examples:

• 내일 비 온대. = They say it’ll rain tomorrow.
• 그 영화 재미있대. = I heard that movie is fun.

It sounds more like passing on advice.

Because of 좋대, the speaker sounds like they are saying:

• I heard it’s a good idea
• They say it’s better to do that

If the speaker wanted to give a more direct recommendation, they might say:

• 기침이 오래가면 검사를 받아 보는 게 좋아.
• 기침이 오래가면 검사를 받아 보는 게 좋겠어.
• 기침이 오래가면 검사를 받아 보세요.

So 좋대 softens the speaker’s ownership of the advice.

Yes. This is casual spoken Korean.

The ending 좋대 is informal, so you would use it with:

• friends
• family
• people younger than you
• casual conversation

A more polite version would be:

• 기침이 오래가면 검사를 받아 보는 게 좋대요.

Or a more directly polite recommendation:

• 기침이 오래가면 검사를 받아 보시는 게 좋아요.
• 기침이 오래가면 검사를 받아 보세요.

Yes, you may see both.

When 보다 is used as an auxiliary verb meaning something like try doing, spacing can vary in actual writing. So both of these are commonly seen:

• 검사를 받아 보다
• 검사를 받아보다

Writers and style guides may prefer one or the other depending on context and editing style, but for a learner, the important thing is to recognize that the meaning is the same here.

Korean often leaves that kind of subject unstated when it is obvious from context.

In this sentence:

• 기침이 오래가면 sets up the situation: if a cough lasts a long time
• then 검사를 받아 보는 게 좋대 means it’s good to get examined

The understood meaning is:

• the person who has the cough should get examined

Korean does this all the time. If English translated every omitted subject literally, it would sound unnatural, so English usually fills it in automatically.