29. Edward, you play so well, But I ______ you played the piano. (A). didn’t know (B). hadn’t known (C). don’t know (D). haven’t known

31. The computer was used in teaching. As a result, not only____, but students became more interested in the lessons. (A). saved was teachers’ energy (B). was teachers’ energy saved (C). teachers’ energy was saved (D). was saved teachers’ energy