问题补充:
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
答案:
(答案→)A. didn’t know
B. hadn’t known
C. don’t know
D. haven’t known
解析:前句说。Edward,你(钢琴)弹得这么好,可见现在已经知道“你弹钢琴”,不知道是在过去,而不是现在,因此句子用一般过去时。