What do the following words have in common?

OR
USE
ZEN
SAGE
MAIN
GEAR
WAGER
NATION

HINT:
#1: The same two letters will change each word into a new one.
#2: The two letters precede each clue.

Answer:

Each word can be changed into a new one when it is preceded by DO:

DOOR
DOUSE
DOZEN
DOSAGE
DOMAIN
DOGEAR
DOWAGER
DONATION

Credit: LA Times Crossword
Sylvia Burxztyn and Barry Tunick
DO TELL