my,mine的用法

不用的~這個字並沒有眾數或單數之分
而my和mine的分別,就是

例如:這是我的書
用mine可以寫成 This is mine / This book is mine
用my就要寫成 This is my book
mine用在句子的最後 而 my 就會用在句子的中間
而且mine之後,不會有名詞

no
mine doesn't need an 's behind it because the word's meaning already includes it....
then you might ask, what about you and yours?
here is a diagram (sort of) to repersent them...

you ---- your ---- yours
me ---- my ----- mine

however these two words are 'speical'...
most of the time an 's is just added to the end of the noun
for example

it ----- it's ----- it's
her --- her's --- her's

note that this 's mean 'it belongs to'
it is different from the short form of (noun) is
for example, using he
if it means it belongs to him, we will use (his)
but if it is just short for he is, we use (he's)
once again I and you are different from other words...
I --- I am --- I'm
you --- you are --- you're

again most of the time an 's is just added to the end of the word, eg
the dog is sleeping ----- the dog's sleeping
the cat is playing --- the cat's playing

so to tell the difference between 's for belonging to and 's for short, we have to look at the word after the 's
after, not before
if the word after the 's is a noun, it means the 's is for it belongs to
if the word after the 's is a verb, it is just a short form of something is

hope you understood that.....