Task: Question Generation
Input (English): #1 return sir arthur conan doyal 
#2 return mum of #1 
#3 return dad of #1 
#4 return when  did  #2 die 
#5 return when  did  #3 die 
#6 return #4 , #5
Output (English): when did sir arthur conan doyals mum and dad die?