adj. challengeable
玛息阿觉得他长笛吹得比阿波罗好，便向这位神发出挑战。
Marsyas thought he could play the flute better than Apollo and challenged the god to a contest.
1829年3月12日，牛津首先向剑桥发出挑战。
On March 12, 1829, Oxford sent a challenge to Cambridge first.
第3位总统候选人上场郑重发出挑战，令这次竞选充满悬念。
A third presidential candidate emerged to mount a serious challenge and throw the campaign wide open.
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