Choose the correct verb form. a) how long has dmitry been living / does he living / in astana? b) how long has omar been studying / does he study / at school n15? c) my freinds has been looking / looked / for a bike for 3 week d) i wrote / have been writting / this exercise since 4 o'clock p.m. e) i am tired because i wrote / have been writting / this exercise since 4 o'clock p.m.