问题补充:
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
答案:
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。