The contraction: "today's..." is normal everyday english and should be accepted but it wasn't (I mean 'was not').
Agree, but maybe not as common as those involving pronouns. Or let's say, contracted forms of "noun + 's" combinations (today's/Mike's working today/Nicole's at the station etc.) are even more informal than "pronoun + 's/'re" (I'm, You're, he's, she's etc.) contractions.
Verbs too are perhaps more common and I've found that DL is inconsistent with their use, sometimes accepting a verb contraction, sometimes not. But thanks for posting.
What they probably wanted to say is 'It's an ordinary day today', (not an unusual one).
Posso usare giornata nel questa sentenza ? Scusami per il mio italiano, però lo studio da 3 mese alla facoltà.
I type the correct answer in and it always states Im wrong, but shows exactly what I type in ?????