遡

go upstream

trace the source

遡[sù]

-（逆着水流的方向走）goagainstthestream:
goupstream溯流而上
-（往上推求或回想）traceback;recall:
recallpastevents回溯往事

他追踪自己的世系上溯至一个古老的诺曼家族。
He traces his descent back to an old Norman family.

该项法规具有追溯效力。
The legislation was made retrospective.

我们两国之间的往来可以追溯到上个世纪。
The assiciation between our two countries can be traced back to last century.

这个家族的历史可以追溯到十七世纪。
The family can trace its history to the 17th century.

警方追溯了被谋杀者当时的动作。
The police retraced the movements of the murder victim.

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