Answer the following questions : 1 . have you bought this book ? 2. when did you buy it ? 3.have you seen this play ? 4 . when did you see it ? 5 . have you made this dress yorself ? 6 . when did you make it ? 7. what were you doing at 7 last night ? 8 . were you knitting at that moment ? 9. what were you reading when i entered ? 10. what were you singing when he came ? 11 . why were you laughing when you saw him ? 12. why was the baby crying ? 13 . what were you doing when we rang you up ? ,14 . what were they writing when the tracher entered ? 15 . what was he listening to when you called him ? 16 . what were you reading when the door-bell rang ? 17 . where were you doing to when i stopped you ? 18 . where was the boy running when you saw him?