​A. What instrument can you play?

I can play the piano. ✔

​

B. 1. Hi, Doldol. ✔ ​(Punctuation)

​

   2. Who? X

    Who's she?=> Corrected : The sentence is corrected grammatically. 

​

   3. She is my friend simsoon​X

     She's my friend, Simsoon. 

(Punctuation)

​(Capitalization)

​=> Corrected : The sentence is corrected grammatically. ​