Give the plural of these nouns univercity sky party way leaf thief ski key tragedy comedy day taxi story language knife

University — universities,
sky — skies,
party — parties,
way — ways,
leaf — leaves,
thief — thieves,
ski — skis,
key — keys,
tragedy — tragedies,
comedy — comedies,
day — days,
taxi — taxis (или taxies),
story — stories,
language — languages,
knife — knives.