Ha!

I beat 20 questions. I beat it up. I thought of cello, and it couldn't guess it. Here is the result:
Knowledgebase Updated
Contradictions:
A cello is comforting
A cello is commonly used
It does not matter if our answers disagree, overtime my answers will change to reflect common knowledge.
The best way to fix these contradictions is to play again.

Things I didn't know:
A cello is not in charge
You cannot play games with a cello
A cello is not multicolored
A cello cannot be washed
You don't make something with a cello
A cello is not considered helpful to humans
A cello is not something you bring along
A cello does have a hole in it