All those second-hand goods are sold at before.A. 30% as lower price asB. as 30% low price

All those second-hand goods are sold at before.
A. 30% as lower price as
B. as 30% low price as
C. 30% as low a price as
D. 30% lower price than

A. 30% as lower price asB. as 30% low price as(答案→)C. 30% as low a price asD. 30% lower price than解析：考查倍数的表达：倍数+as+adj+a/an+as结构， 30％是倍数， as low a price as 是固定搭配，不能调换词的顺序的。句意：这些二手商品比之前的要便宜百分之三十。选C。

我明天再问问老师，叫他解释下这个问题