-얄미는 이번 일요일에뭘 할거래?

What will talme do this Sunday?

=> Another way: Your sentence is okay and this is another way of saying it.

What's Yalmi going to do his Sunday? 

-우리랑 같이 갈수 있대.재미 있겠다.

She can go to with us. It would be fun. --> She's going to join us. It'll be fun.

=> Corrected : The sentences are corrected grammatically.

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-만나서 반가워,심순아.

Nic to meet you Simsun. --> Nice to meet you, Simsoon.

=> Corrected : The sentences are corrected grammatically.​​