foot→feet,

　　goose→geese,

　　tooth→teeth,

　　child→children,

　　man→men,

　　woman→women,

　　sheep→sheep,

　　deer→deer,

　　mouse→mice.

　　某些外来词变复数：datum→data,medium→media,bacterium→bacteria,curriculum→curricula,criterion→criteria,phenomenon→phenomena.(um/on→a)analysis→analyses,basis→bases,crisis→crises,diagnosis→diagnoses.(is→es)