值此9·11五周年纪念之际，“Ground zero”再度成为新闻媒体的热门词汇。看外电的相关报道，为什么“悼念罹难者的地方”常用ground zero来指代？

Mourners pay their respects beside

a reflecting pool at Ground Zero on the fifth

anniversary of the September 11, 2001 attacks

 on the World Trade Center on September 11, 2006. [Reuters]

Ground zero原指“常规导弹瞄准的目标、核设备的爆炸点”，当然，一旦这个“点”被击中，“点”则就延伸为“废墟”了。由此，美国9·11事件后，ground zero常用来指代被恐怖分子袭击后的“世贸大厦遗址”。

看下面一个例句：As at the commemorations at Ground Zero, family members read the names of the dead in a solemn ceremony against a sound track of somber¹ and patriotic² music. （在世贸大厦遗址举行的纪念活动上，罹难者家属在低沉的爱国主义乐曲中念着遇难亲友的名字。）