我注视著父母和祖父母的相片，努力想像他们的父母是什么样子，就这样一直想下去回溯数代，追溯久远。
I looked at pictures of my parents and grandparents and tried to imagine their parents, and so on, back through the generations, back and back through time.
你不能追溯到2003年，因为你只能回溯一年。
You cannot retroactive to year 2003, because you can retroactive only one year.
一个新的摄谱仪回溯数十亿光年远的宇宙绘制宇宙网状结构图，并追溯宇宙中生命基本元素的分布。
A new spectrograph slices across billions of light-years to map the filamentary structure of the universe and trace the distribution of elements that are fundamental to life.
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