"Men are children."
Translation:Les hommes sont des enfants.
My guess... is that because des signifies ownership of some quality, but to specify men as being the subject of the sentence, les must instead be used. ie. des is only used in front of the object (children) of the verb (which in this case is 'are').
This is 100 percent right. Duo got this wrong. It doesn't say "the men" it says "men in general".
I wrote this "hommes sont des enfants" Why do we need "the"? I mean it's not there in the sentence.