br/r –  brush/rush, brain/rain

br/b –  broom/boom, break/rake

cr/r – crash/rash, crane/rain

cr/c –  crash/cash, crane/cane

dr/r – draw/roar, drip/rip

dr/d – draw/door, drip/dip

fr/r – fright/right, fried/ride

fr/f – fright/fight, frog/fog

gr/r – grip/rip, ground/round

gr/g – grill/gill, grate/gate

pr/r – price/rice, pram/ram

pr/p – prick/pick, pray/ray

tr/r – tray/ray, train/rain

tr/t – trick/tick, trip/tip