an ox - oxen
a knife - knives
a watch - watches
an address addresses
a child - children
a foot - feet
a potato - potatoes
a sheep - sheep
a factory - factories
a toy - toys
a deer - deer
an ox - oxen
a knife - knives
a watch - watches
an address addresses
a child - children
a foot - feet
a potato - potatoes
a sheep - sheep
a foot - feet
a factory - factories
a toy - toys
a deer - deer