单选题 Some laws formalize long accepted customs, while others impose norms ______previously mandated by the populace.

【正确答案】 A

【答案解析】解析：本题考查省略句的否定表达。逗号前后为并列句，主谓宾成分均完整，故排除带有动词的[B]项、[C]项和[D]项。______ previously mandated by the populace为省略了which are的定语从句，修饰norms。