问题补充：
The bell the end of the period rang and we had to stop our discussion
A. indicating
B. indicated
C. to be indicated
D. being indicated
答案：
(答案→)A. indicating
B. indicated
C. to be indicated
D. being indicated
解析：考查现在分词做定语;句意：代表这段时期结束的铃声响了，我们不得不停止我们的讨论。这句话中and 连接两个句子，and前面的句子主语为the bell indicating the end of period，动词是rang。indicating the end of period 修饰the bell.。一个单句不可能有两个主谓，又因为“铃声”和“预示”是主动关系，所以indicate要用现在分词形式indicating。而不能用表被动的indicated .
