We think white looks good _____ you, but people with black skins don't look good ______ white. [ ]

A. on, on

B. in, in

C. on, in

D. in, on

在先左后右的原则下，根据访问根结点的次序，二叉树的遍历可以分为三种：前序遍历、 【1】 遍历和后序遍历。