1. 그건 뭐니?

 What is it? ✔​ ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

2. 내 여자 친구야.

 This is my girlfriend. ​------> ​She's my girlfriend.

3. 너 놀리는 거지? 그거 한번 보여줘봐.

 Are you kidding me? Show me that. ------> You're kidding me. Let me see it.