His dog doesn*t play in the garden/
Does his dog play in the garden?
Ann*s mother isn*t cooking a cake in the kitchen now.
Is Ann*s mother cooking a cake in the kitchen now?
P.S.В вопросе (вашем) - ошибка. ДОлжно быть так Ann's mother is cookштп a cake in the kitchen now, а у вас там просто cook без ing-ового окончания.