Task: Question Generation
Input (English): Context : The 2015 Bahrain Grand Prix (formally known as the 2015 Formula 1 Gulf Air Bahrain Grand Prix) was a Formula One motor race that was held on 19 April 2015 at the Bahrain International Circuit in Sakhir, Bahrain. 
Answer : 19 April 2015
Output (English): What is the date when 2015 Bahrain Grand Prix happened?