杠杠上填serving 还是served 为什么?China says that the Diaoyu islands have been part of its territory since ancient times,———— as important fishing grounds administered by the province of Taiwan.

杠杠上填serving 还是served 为什么?
China says that the Diaoyu islands have been part of its territory since ancient times,———— as important fishing grounds administered by the province of Taiwan.

主语是 钓鱼岛,所以应该填serving充当,作为,而不是被用作…………希望帮到你了,如果没有请忽略我.