Rescuers are for the safety of the two men trapped in the mine.
A. grateful
B. concerned
C. extreme
D. frightened
网友回答
A. grateful
(答案→)B. concerned
C. extreme
D. frightened
解析：句意：营救人员为困在井下的两个人的安全担心。be concerned for/about 为……担心忧虑；be grateful to sb for sth 因某事而感谢某人；extreme极度的；frightened恐惧的。根据句意，可知选B。