Question:
Who was the chair of European Central Bank in May, 2015?

Context:
 Wim Duisenberg is the chair of European Central Bank from Jun, 1998 to Nov, 2003. 
 Jean-Claude Trichet is the chair of European Central Bank from Nov, 2003 to Oct, 2011. 
 Mario Draghi is the chair of European Central Bank from Nov, 2011 to Oct, 2019. 
 Christine Lagarde is the chair of European Central Bank from Oct, 2019 to Dec, 2022.

Answer:
Question:
Who was the chair of European Central Bank in May, 2015?

Context:
 Wim Duisenberg is the chair of European Central Bank from Jun, 1998 to Nov, 2003. 
 Jean-Claude Trichet is the chair of European Central Bank from Nov, 2003 to Oct, 2011. 
 Mario Draghi is the chair of European Central Bank from Nov, 2011 to Oct, 2019. 
 Christine Lagarde is the chair of European Central Bank from Oct, 2019 to Dec, 2022.

Answer:
user
Mario Draghi
assistant
Question:
Who was the chair of European Central Bank in May, 2015?

Context:
 Wim Duisenberg is the chair of European Central Bank from Jun, 1998 to Nov, 2003. 
 Jean-Claude Trichet is the chair of European Central Bank from Nov, 2003 to Oct, 2011. 
 Mario Draghi is the chair of European Central Bank from Nov, 2011 to Oct, 2019. 
 Christine Lagarde is the chair of European Central Bank from Oct, 2019 to Dec, 2022.

Answer:
user
Wim Duisenberg
Christine Lagarde
Jean-Claude Trichet
assistant
Question:
Who was the chair of European Central Bank in May, 2015?

Context:
 Wim Duisenberg is the chair of European Central Bank from Jun, 1998 to Nov, 2003. 
 Jean-Claude Trichet is the chair of European Central Bank from Nov, 2003 to Oct, 2011. 
 Mario Draghi is the chair of European Central Bank from Nov, 2011 to Oct, 2019. 
 Christine Lagarde is the chair of European Central Bank from Oct, 2019 to Dec, 2022.

Answer:
user
Mario Draghi
assistant