cyclic
cyclical
secondary
advocate
agent
alter ego
alternating
alternative
amicus curiae
analogy
attorney
back and fill
back-and-forth
backup
backup man
bandy
battledore and shuttlecock
be here again
be quits with
beating
champion
change
changeling
circle
circling
come again
come and go
come around
come round
come round again
come up again
commute
comparison
compensate
complementary
cooperate
copy
corresponding
counterchange
counterfeit
cover
cycle
deputy
dither
do a hitch
do a stint
do a tour
do time
double
dummy
ebb and flow
enlist
alter
change by reversal
con
fill-in
learn
memorise
memorize
relief
reliever
reverse
stand-in
substitute
turn
vary
alternated
alternates
above
continuous
final
multiple
previous
successive
vertical