问题补充:
Listen! Can you hear them in the next room?
A. practising to sing
B. practising singing
C. practise singing
D. to practise sing
答案:
A. practising to sing
(答案→)B. practising singing
C. practise singing
D. to practise sing
解析:句意:听!你能听到他们在隔壁的教室练习唱歌吗?hear sb doing sth听见某人正在做某事;practise后面接动名词形式,故选择B。