想問樣野._.

carmenkaka

it depends on the second to the last letter

eg. study; the second to the last letter is D, it is NOT a VOWEL, so it uses " -ies "
play; it is "A", it IS a VOWEL, so it uses " -s "

more examples:
turkey, turkeys; (e)
monkey, monkeys.. (e)

worry, worries; (r)
hurry, hurries;  (r)
baby, babies (b)


same also to the case when you want to change it into NOUN
like.. CRAZY --> CRAZINESS; LAZY --> LAZINESS


Hope you can understand; I don't know if i can use Chinese to reply, so I used English
if you still couldn't understand, you're welcome to PM me =D