The Genitive case is used in certain expressions, e.g. to identify color, gender, and aspect:
Какћго цвљта ітот карандђш?	What color is that pencil?
Какћго рћда слћво «рџчка»?	What gender is the word рџчка?
Какћго вќда глагћл «читђть»?	What aspect is the verb читђть?