With nouns ending in o preceded by a consonant, the plural in many cases is spelled by adding -es (pronounced /z/):
hero heroes
potato potatoes
volcano volcanoes or volcanos
However many nouns of foreign origin, including almost all Italian loanwords, add only -s:
canto cantos
hetero heteros
photo photos
zero zeros
piano pianos
portico porticos
pro pros
quarto (paper size) quartos
kimono kimonos
维基百科是这么说的，外来词，包括拉丁词，只加s