翻译~~谢绝机器翻译!Earth is a target in a cosmic shooting gallery, subject to random violent events that were unsuspected a few decades ago.为什么上面那句说明了这个？Until recently, nobody realized that Earth is exposed to unpredictable violent impacts from space.
问题描述：
翻译~~谢绝机器翻译!
Earth is a target in a cosmic shooting gallery, subject to random violent events that were unsuspected a few decades ago.
为什么上面那句说明了这个？Until recently, nobody realized that Earth is exposed to unpredictable violent impacts from space.
答
地球是宇宙星体的一个靶子，毫无疑问，在很多年前遭受过很大的撞击。
到现在为止，没有人预料到地球可能遇到哪些来自宇宙的不明撞击
答
地球是宇宙射击场的靶子，受不定期暴力事件的影响。这些暴力事件几十年前并不为人所知。
答
在宇宙这个打靶场里,地球是个易受随机暴力袭击的一个目标.而遭受暴力袭击这个事情,几十年前人们一无所知.
直到最近为止,没有人意识到地球暴露在（宇宙）空间里毫无预兆的暴力袭击之下.