AIDS control and prevention is a to China as well as the whole world．
A. surprise
B. challenge
C. reaction
D. threat
网友回答
A. surprise
(答案→)B. challenge
C. reaction
D. threat
解析：考查名词辨析：A．surprise 惊讶，B．challenge挑战，C．reaction反应D．threat威胁，句意是：艾滋的控制和预防对中国乃至全世界都是挑战。选B。