Translation:What is the color of their skin?
Five months later, it was still not accepted today in a web strengthening review exercise. In fact, Duolingo rubbed salt in the wound by remonstrating, "Pay attention to the accents. Ποιο είναι το χρώμα του δέρματος τους;"
It's been there for five months. You may have another error or there may be a computer glitch. Please send a screenshot.
What's the difference between "δέρμα" and "δέρματος"? Is it case or something else?
Yes! "Δέρμα"=Skin (Nominative), "Δέρματος"=Of the skin (Genitive) ;)
("Δέρματός τους" is the correct one, btw)
Thanks! Is that the case for all singular α nouns? For instance του θεματος (of the theme)?
Yes! This category of nouns is called "imparisyllabic neuter nouns ending in -(μ)μα" ;)