a. 挑战的, 引起争论的

challenge/challenging/champion/championship/change
记忆：
1. challenge [ 5tFAlindV ] n. 挑战 Be brave to meet the challenge, or you will be rejected tomorrow. 勇敢面对挑战，否则你明天会被淘汰。
2. challenging [ 5tFAlindViN ] a. 挑战性的 I like to do the challenging work. 我喜欢做有挑战性的工作。
3. champion [ 5tFAmpjEn ] n. 冠军，优胜者 German team won the champion again. 德国队又获得了冠军。
4. championship [ 5tFAmpjEnFip ] n. 锦标赛 Chinese table tennis team did quite well in the championship. 中国网球队在锦标赛中做得很好。
5. change [ tFeindV ] n.& v. 改变 What has changed him that much?什么东西使他变化那么大？
另类阅读：
To win the champion in the World Bicycle Championship is quite challenging. You need some change so as to meet the challenge.

轻松一刻
CEO: "My wife made a millionaire out of me."
Assistant: "What were you before?"
CEO: "a multimillionaire."