Образовать множественное число: boot , ox, fox, wom¬an, mouth, mouse, goose, deer, ship, sheep, crisis, nucleus, formula, room-mate, man-of-war, boy-messen¬ger, passer-by.

boot - boots
ox - oxen
 fox - foxes 
woman - women
mouth - mouths
mouse - mice 
goose - geese 
deer - deer 
ship - ships
sheep - sheep
crisis - crises
nucleus - nucleuses
formula - formulae
 room - rooms 
mate - mates 
man-of-war - men-of-war 
boy - boys
messenger - messengers
passer-by - passers-by