Never before in China so carefully concerned about the food safety.
A. people have been
B. have people been
C. are people
D. people are
网友回答
A. people have been
(答案→)B. have people been
C. are people
D. people are
解析：考查倒装。Never，表否定意义，表否定意义的词放在句首时，句子要用部分倒装，排除A,D;根据时间状语before，可知不能用一般现在时态，排除D。所以选B。