answer: David will take the old books he bought to America. He tells #Person1# whether he comes back to China depends on his mother's health.
documents: #Person1#: David, where did you get so many old books?
  #Person2#: Some graduates were selling their used books. They were really cheap so I bought some.
  #Person1#: But aren't you leaving China in 2 weeks? How can you finish reading so many books?
  #Person2#: I'll take them back to America. I want to continue to improve my Chinese so they'll be very helpful.
  #Person1#: When will you come to China again?
  #Person2#: I don't know. Maybe several years later or maybe next year. That all depends.
  #Person1#: Depends on what?
  #Person2#: It depends on whether my mom will recover or not. If she is still ill, I cannot leave her to work in China.