"The crab drinks water."
Translation:Το καβούρι πίνει νερό.
When we speak about something general, we don't use articles. We say "πίνει νερό" =she is drinking water/she drinks water, generally! But if you want to say "she is drinking her own water", then you put the article, because you specified it "πίνει το νερό της", "τρώει το φαγητό της", Another example: Παιζει κιθάρα = she is playing guitar (generally), but "παίζει την κιθάρα της"= she is playing her guitar. (Specified). "Φοραει παντελονια"="He/she wears trousers" (generally), but "φοράει το καινούριο παντελόνι"= he/she wears the new trousers.(specific)
BUT when you say "μου αρέσει" = I like,+noun, you always put an article. "Μου αρέσει O ήλιος" (I like the sun), "του αρέσουν ΤΑ παιχνίδια"= he likes games. So "he likes playing games" is "του αρεσει να παιζει παιχνίδια"
I hope that helped..