B. He can't prove his age.
C. My secret is cow's milk.
D. Singh is lying about his age.
E. I am not only the oldest athlete in the world.
F. We understand that he has never known his real age.
G. I think the people who have accused me of lying are jealous.
Przekształcając zdania na mowę zależną, trzeba pamiętać również o tym, aby zamienić zaimki osobowe, czas i miejsce!