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Hi, this is the part of grammar that confuses me the most.

For names ending in -s is it always good form to add the s' at the end? For example: Thomas' dog or Charles' house or are there exceptions?

P.S. I sometimes see written down: the dog's bark and the dogs' barks, because in the second example dogs is plural.

Many thanks in advance, and as much information would be greatly appreciated.
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the dog's bark-- one dog

the dogs' barks-- more than one dog
Thomas's dogs-- one Thomas
Thomases' dogs-- more than one Thomas
Socrates' philosophy-- one Socrates
Socrateses' philosophies- more than one Socrates.

The point being that modern punctuation prefers the 's after singular nouns-- but not plural nouns-- ending in s, but still recognizes the apostrophe only in certain classical names: Socrates', Moses', Jesus'. Nevertheless, the older way (Charles' dog) is still eminently understandable, and will be corrected only by the most pedantic.
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Many thanks. I'm still finding it difficult to grasp though. Does your reply stay anywhere on my profile, if I need to look back on it?
No, it will drift away slowly. Start a text file, copy and keep it on your computer: that's what I do.
What an excellent idea; I shall do that in the future to remind me of the grammatical cases that I am unsure of. [Y]
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