ABSTRACT
Kакой, какая, какое, какие ‘which’ is used to ask for details about the object or person under discussion. Kакой etc. is an adjective and therefore agrees in number, gender and case with the noun it is qualifying: Вы о какой книге говорите? ‘What (which) book are you talking about?’ (literally: ‘About which book … ?’). (See Basic Russian, Unit 19.)
