"The turtles eat the rice and the tomato."
Translation:Skildpadderne spiser risene og tomaten.
From what I have seen, risen can also mean the portion of rice or the dish of rice and the plural is used when there is more than one person or animal eating.
http://sproget.dk/lookup?SearchableText=ris "ris" can be a plant of rice, a grain of rice, a portion or dish of rice, one (thing) of rice "risen" is "the rice" and follows above meanings with "the" instead of "a". "risene" is used for talking about the many grains of rice or multiple portions of rice. (Eat all your rice. or They eat the rice.) and I think also for multiple kinds of rice. I hope someone will correct me if I am wrong? http://da.wikipedia.org/wiki/Ris .
never heard anyone say 'rices' even if more than one person is eating one or more rice dishes ... see what I did, the plural is on the DISH, not the content. I am married to a Dane and she can't think of a situation where she would use 'risene'. The Danish online dictionary gives 'ene' as a plural ending but not one example of how it would be used.