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challenge
形容词: challengeable 过去式: challenged 过去分词: challenged 现在分词: challenging 第三人称单数: challenges
n.挑战;邀请比赛;盘问;质疑
v.向 ... 挑战;盘问;质疑
例句：用作名词 (n.)
The crossing of this dangerous river was a challenge to most of us.
对我们大多数人来说,横渡这条充满危险的大河确实是个挑战。
He accepted his friend's challenge to swim across the river.
他接受朋友提出的挑战，游过这条河。
用作动词 (v.)
Nowadays no one will challenge the fact that the earth is round.
现在没有人会对地球是圆的这一事实提出异议。
New competitors are emerging to challenge the old economic arrangements.
新的竞争对手正在崛起，向旧的经济布局挑战。
