answer: #Person2# tells #Person1# the River Nile is a long river in Africa and people built the Aswan High Dam to control the flood and make electricity.
documents: #Person1#: Are there any long rivers in Africa?
  #Person2#: Yes, for example, the River Nile is the longest fiver in the world.
  #Person1#: Is it Egypt? I hear that it used to flood large areas. What about it today?
  #Person2#: In order to control the flood and make electricity, people built the Aswan High Dam on the river.
  #Person1#: Then it is another interesting place, isn't it?