The Diaoyu islands have been part of China’s territory since ancient times as important

问题补充：

The Diaoyu islands have been part of China’s territory since ancient times, as important fishing grounds of Taiwan.

A. served

B. to serve

C. serving

D. having served

答案：

A. served

B. to serve

(答案→)C. serving

D. having served

解析：考查分词做状语。当做分词的动词与句子的主语构成主动关系的时候就使用现在分词做状语，当二者构成被动关系的时候就使用过去分词做状语。本题的The Diaoyu islands与serve构成主动关系吗，故使用现在分词的形式。故C正确。B项表示将来。