In western culture,21 was the age young people traditionally received a key to their paren

In western culture,21 was the age young people traditionally received a key to their parents’ door, as a symbol of entering adulthood.
A. in which
B. on which
C. at which
D. to which

A. in whichB. on which(答案→)C. at whichD. to which解析：本题考查定语从句。先行词age与介词at搭配。句意：在西方传统文化中，年轻人到了21岁便可获得进入父母房间的钥匙，象征着他们开始进入成人世界。

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