пока(обычно употр-ся с глаголом в отрицат. форме, отрицат. местоимением или прилагательным с "не-": The cause of the fire is unknown as of yet. – причина пока неизвестна • We don't know the cause of the fire as of yet. – пока не знаем • As one might imagine, Eshed's statements have prompted many to seek comment or confirmation from the Israeli government or military, but neither have offered any response as of yet.coasttocoastam.comART Vancouver)
пока ещё(в предложениях с отрицанием: there have been no letters from him as yet – от него ещё пока нет писем • No one has found a solution as yet. • Zack has not given this plan a name as yet.)