What do the items in the following lists have in common?

List A
Aspirin
Escalator
Linoleum
Nylon
Yo-yo
Zipper

List B
Susan B. Anthony
Ludwig van Beethoven
J. Edgar Hoover
Ralph Nader
Florence Nightingale
Henry David Thoreau
Isaac Newton

List C
African elephant      640
Rhinoceros               560
Giraffe                      450
Cow                          280
Orangutan                 275
Human being            267
Reindeer                   246

Answers:

List A: Brand names that have become generic terms
List B: Notable people who never married
List C: Gestation periods (in days)