Aha, the story is slowly unwrapping itself. "I see a dog but it is not yours" ... and you're going to wait until I have found him... I know.
"The children write on the shark". ..."What do you see on the shark?"... we'll slowly find out whether the sharks writings and the searched-for dogs are from two stories or from the same one ;-)
This sentence has two parts and each of them needs a subject, especially if the two parts have different
subjects as in this case:
Isee a dog but
itis not yours
subject (and the verb) is the same, you can skip it:
Isee my dog but
Ido not see yours
Isee my dog but not yours
This is a bit ridiculous, I refuse to translate "però" in the exact same way that I translate "ma" otherwise there would be no need to have two words that describe the same thing. I looked up però and it also means "though", but that isn't accepted. Wonder if I should report this...