"The claws of the bear are enormous" was not accepted. Pretty literal translation, perfectly natural English sentence.
EDIT: I guess it's a slightly more general meaning than the English sentence implies? But how would I know that from the sentence?
I suspect that if you had typed 'of a bear' instead of 'of the bear' it would have been accepted.
It's something that always catches me as well: Le/la = the; un/une = a. DL is very picky about this.
There's only one bear, though. That part isn't plural. The only weird translation thing here is that 'les' is used in French (as in "the") where it doesn't have to be used in English but can be.
i.e. The claws of a bear are huge is an acceptable translation. Or A bear's claws are huge but that's a less direct translation.
"The claws of one bear are enormous" Didn't accept. Didn't accept the "one" why? Thank you!
Because une can mean either "a" or the numeral "one". In this case it clearly means "a".
why I cannot write " the bear's claws " instead of " a bear's claws " , is a wrong grammar ?
The grammar is okay but the French says un ours, which is "a bear". Not l'ours = the bear.
However, the grammar of your question is bad. Use a contraction and inversion to form a negated question in English. "Why can't I write...." (Cannot is a semi-auxiliary verb.)