chinguga naeil susureul bada.

My friend will have surgery tomorrow.

Breakdown of chinguga naeil susureul bada.

• 친구: friend
• 내일: tomorrow
• 받다: to receive
• 수술: surgery; operation

Questions & Answers about chinguga naeil susureul bada.

Why is 가 used after 친구 instead of 는?

친구가 marks friend as the subject of the sentence.

In Korean, 가/이 is the subject marker, while 는/은 is the topic marker. In a simple sentence like this, 가 often sounds natural when you are just stating a fact:

• 친구가 내일 수술을 받아.
  My friend is having surgery tomorrow.

If you used 친구는, it would feel more like you are setting up my friend as the topic, often with some contrast or added context:

• 친구는 내일 수술을 받아.
  As for my friend, he/she is having surgery tomorrow.

So 가 here is the more neutral subject-focused choice.

Why does 친구 not have 내 or 제 in front of it? Does it still mean my friend?