【题目】AIDS control and prevention is a to China as well as the whole world．
A. surpriseB. challengeC. reactionD. threat
在线课程【答案】B
【解析】
考查名词词义辨析。句意：艾滋的控制和预防对中国乃至全世界都是挑战。A．surprise 惊讶；B．challenge挑战；C．reaction反应；D．threat威胁。由“AIDS control and prevention”可知，challenge“挑战”符合句意。故选B项。