足金首饰在销售或佩戴中，要避免接触（），以免受侵蚀，使足金首饰出现斑点。
A.不锈钢
B.铁
C.银
D.水
参考答案：C
Although Rio knew little about marketing, he succeeded _____ other more well-informed managers failed. [ ]
A. as
B. unless
C. what
D. where
