In English, one does not say *"If someone have a patience". There are two things wrong with that sentence: you have not conjugated "to have" for third-person singular (as "someone" is neither the speaker nor the addressee and there is only one "someone" ) which would be "has". Secondly, you are saying *"a patience", which is not allowed, because "patience" is an uncountable noun – one cannot count "patiences" i.e. *"I have six patiences".If someone have a patience please explain how works "could have; should have; would have"
Now, onto the topic at hand,
Could have denotes an action or a state that had the possibility of happening under a certain condition in the past.
"If you had given me the book, I could have put it under the right section."
Would have denotes an action or a state (I can't think of any other way of putting this) would have happened under a certain condition in the past.
"If you had given me the book, I would have put it under the right section."
Shoud have denotes an action or a state that ought to have happened but did not.
"You should have given me the book; I would have been able to put it under the right section."
I hope that you have understood – if there is something you still need help with, just ask.
[Not a teacher]
Student or Learner