Singular  Plural  Singular  Plural 
bamboo bamboos ratio ratios
casino casinos scenario scenarios
commando commandos silo silos
disco discos shampoo shampoos
duo duos solo solos
dynamo dynamos stereo stereos
ghetto ghettos studio studios
kangaroo kangaroos tattoo tattoos
kilo kilos trio trios
photo photos video videos
piano pianos zero zeros
radio radios zoo zoos