Hello @khangdo and welcome to the Neo4j Community.
Unfortunately, you graph is not correct so your answers are wrong.
Is it possible that you added relationships more than once?
I suggest that you do the following:
Go to the sandbox site and terminate the sandbox for the course. (right down arrow to see the sandbox actions)
Refresh the Challenge page in the course. It will take a minute or so the the new sandbox to be created. (wait until you see $neo4j in the embedded sandbox pane.
Always use the embedded sandbox for your work in the challenges as it has the code to reset the sandbox for the challenge and validate your work.