Which company invented the first portable CD player?
user
I’m not sure. Maybe Sony?
assistant
Do you know Sony'
user
No.  Sorry, I don’t know that.
assistant
Which company invented the first portable CD player?
user
I’m not sure. Maybe Sony?
assistant
Do you know Sony'
user
I’m sorry, I’m not sure. I’m not an expert on that topic.
assistant
Which company invented the first portable CD player?