answer: #Person1# could sing 'O Canada' since young.
documents: #Person1#: The Canada Day is on the 1st of July. 
  #Person2#: What is its national anthem? 
  #Person1#: The national anthem of Canada is 'O Canada'. 
  #Person2#: Can you sing the song? 
  #Person1#: Yes, I could sing it when I was very young.