【题目】 (2012年潍坊市高三质量检测)A harmonious society is like a symphony or orchestra－
each person contributes a small sound，but when________with other sounds，it becomes beautiful music.
A．combining
B．being combined
C．combined
D．to be combined
在线课程【答案】C
【解析】考查非谓语动词的用法，when后承前省略了it was，所以要用过去分词表被
动 。