【题目】Finding information in today's world is easy. The________ is how you can tell if the information you get is useful or not.
A.knowledge
B.ability
C.competition
D.challenge

【答案】D
【解析】考查名词。句意：当今世界找信息很容易，但困难的事是你如何辨别你所获得的信息是否有用。A. knowledge"知识"；B.ability”能力”；C.competition”比赛，竞赛“；D.challenge“ 挑战，困难的事”，选D。