Who is Simsoon? √
 She is my classmate. She can ride a bike and play piano well. —> She can ride a bike and play the piano well. 
=> This sentence is okay. This is another way of saying it. 
Who is Simsoon? —> Which girl is Simsoon? 
=> This sentence is okay. This is another way of saying it. 
12/22 
Yes, go and say hello. —> Yes she is. Go and say hello to her. 
=> This sentence is okay. This is another way of saying it. 
"Hello? What's the matter? Can you hear me?" 
=> This sentence is okay. This is another way of saying it. 
It smells good. √