Question:
Who was the owner of Drax power station in Apr, 1999?

Context:
 Drax power station is owned by Drax Group from Jan, 2005 to Dec, 2022. 
 Drax power station is owned by AES Corporation from Jan, 1999 to Jan, 2003. 
 Drax power station is owned by National Power from Jan, 1990 to Jan, 1999. 
 Drax power station is owned by Central Electricity Generating Board from Jan, 1974 to Jan, 1990.

Answer:
Question:
Who was the owner of Drax power station in Apr, 1999?

Context:
 Drax power station is owned by Drax Group from Jan, 2005 to Dec, 2022. 
 Drax power station is owned by AES Corporation from Jan, 1999 to Jan, 2003. 
 Drax power station is owned by National Power from Jan, 1990 to Jan, 1999. 
 Drax power station is owned by Central Electricity Generating Board from Jan, 1974 to Jan, 1990.

Answer:
user
AES Corporation
assistant
Question:
Who was the owner of Drax power station in Apr, 1999?

Context:
 Drax power station is owned by Drax Group from Jan, 2005 to Dec, 2022. 
 Drax power station is owned by AES Corporation from Jan, 1999 to Jan, 2003. 
 Drax power station is owned by National Power from Jan, 1990 to Jan, 1999. 
 Drax power station is owned by Central Electricity Generating Board from Jan, 1974 to Jan, 1990.

Answer:
user
National Power
Central Electricity Generating Board
Drax Group
assistant
Question:
Who was the owner of Drax power station in Apr, 1999?

Context:
 Drax power station is owned by Drax Group from Jan, 2005 to Dec, 2022. 
 Drax power station is owned by AES Corporation from Jan, 1999 to Jan, 2003. 
 Drax power station is owned by National Power from Jan, 1990 to Jan, 1999. 
 Drax power station is owned by Central Electricity Generating Board from Jan, 1974 to Jan, 1990.

Answer:
user
AES Corporation
assistant