A. How do Koreans celebrate Children's Day?

We usually celebrate children's day by giving present to child and going to theater or amusement park to make the child happy. 

=> We usually celebrate Children's Day by giving presents to the child and going to theater or amusement park to make the child happy. 

=> Corrected : The sentences are corrected grammatically. 

B. Make these sentences into English.

-내 컴퓨터에 문제가 있어.   :   My computer has problems.

=> There is a problem with my computer.​

=> Your answer is correct but here's another way of saying it.​

-나 중간고사 완전히 망쳤어. : I ruined my midterm exam.

=> I totally messed up the midterm.​

=> Your answer is correct but here's another way of saying it. 

-내가 가방을 버스에 두고 내렸어. : I got off the bus leaving my bag.

=> I've left my bag on the bus.​​

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