Нужно постава множественное число.
fellow-worker, merry-go-round, man-of-war, passer-by,
ster-in-law, forget-me-not, room-mate, lily-of-the-valley,
cket-holder, commander-in-chief, governor-genera

fellow-workers, merry-go-rounds, men-of-war, passers-by,

sters-in-law, forget-me-nots, room-mates, lilies-of-the-valley, ticket-holders, commanders-in-chief, governor-generals

fellow-workers, merry-go-rounds, men-of-war, passers-by,

sisters-in-law, forget-me-nots, room-mates, lilies-of-the-valley, ticket-holders, commanders-in-chief, governors-general

Объяснение: