... When? How long? For and Since Unit 12 When? How long? For and Since A Hãy so sánh When ? (+ Past simple) How long .? (+present perfect): A: When did it start raining? Trời mưa từ vậy? B: ... biết rõ We have known each other for a long time (not “we know”) Chúng biết lâu Are you waiting for somebody? Bạn chờ phải không? How long have you been waiting? Bạn chờ rồi? B I have been doing ... “ How long have you been driving?” Since I was 17.” “Bạn lái xe rồi?” “Từ 17 tuổi.” C I have done (simple) hay I have been doing (continuous): Thì continuous thường dùng với how long, since for...