假如我在我所居住的佐治亚州穿过某个树林时没有看到北美黑啄木鸟或听到它的声音，我是不是就可以说这种鸟不存在呢？
If I walk through a forest in Georgia , where I live , and fail to see or hear the pileated woodpecker , am I permitted to conclude that the bird is absent ?
黑啄木鸟