问题补充:
Mary is often heard playing piano in the next room in the evening.
A. practise
B. to practise
C. practising
D. practiced
答案:
A. practise
(答案→)B. to practise
C. practising
D. practiced
解析:本题考查动词用法。hear sb do sth听说某人做某事,其被动语态中要加上to,故选B。句意:常听说Mary晚上在隔壁房间弹钢琴。