THÌ Q KHỨ HỒN THÀNH TIẾP DIỄN: (Past perfect continuous) Từ nhận biết: • • • • Until then By the time Prior to that time Before, after - Khẳng định (+) : S + had + been + V-ing - Phủ định (-) : S + had not + been + V-ing had not = hadn’t - Câu hỏi (?) Yes, S + had No, S + had not : Had + S + been + V-ing ?