It is important to know what colours look good (a_) your skins.空格里面是a开头的词.
问题描述：
It is important to know what colours look good (a_) your skins.空格里面是a开头的词.
答
at 吧……
答
应该是against吧
against 表示 “衬托，以……为背景”，符合句意。
答
as