Original sentence: 1st Appearance of Barry Allen as the Flash.1st Appearance of Dr.1st Appearance of Hank Pym.1st Appearance of Hulk.1st Appearance of Iron Man.1st Appearance of Silver Age Green Lantern.1st Appearance of Spider-Man.1st Appearance of Thor.1st Appearance of X-Men.1st Appearance of the Fantastic Four.1st Appearance of the Justice League of America.1st Appearance of the Vulture.Second appearance of the Fantastic Four, 1st Appearance of the Skrulls
Edited sentence: First appearance of Barry Allen as the Flash.First appearance of Dr.First appearance of Hank Pym.First appearance of Hulk.First appearance of Iron Man.First appearance of Silver Age Green Lantern.First appearance of Spider-Man.First appearance of Thor.First appearance of X-Men.First appearance of the Fantastic Four.First appearance of the Justice League of America.First appearance of the Vulture.Second appearance of the Fantastic Four, first appearance of the Skrulls