The DiaoYu Island have been part of China’s territory since ancient times as important fi

问题补充：

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

A. served

B. serving

C. to serve

D. having served

答案：

A. served

(答案→)B. serving

C. to serve

D. having served

解析：考察分词做状语。本句中的主语the DiaoYu Island和后面的动词serve as构成主动关系，故使用现在分词在句中作状语。句意：钓鱼岛自古以来就是中国的一部分，作为台湾的一个重要的渔场。故B正确。