動詞 challenge:

1. take exception to
   同義詞：challenge, dispute, gainsay
2. issue a challenge to
   同義詞：challenge
3. ask for identification
   同義詞：challenge
4. raise a formal objection in a court of law
   同義詞：challenge, take exception

形容詞 challenging:

1. requiring full use of your abilities or resources
   同義詞：ambitious
2. stimulating interest or thought
   同義詞：thought-provoking
3. disturbingly provocative
   同義詞：intriguing

1. A mentally challenging problem or puzzle.
   腦筋急轉(zhuǎn)彎一個考驗智力的問題或難題
2. A challenging course of study; a challenging role for an inexperienced performer.
   一門挑戰(zhàn)性的課程; 給一個無經(jīng)驗的演員一個挑戰(zhàn)性的角色
3. They challenged that company's supremacy in the field of electronics.
   他們挑戰(zhàn)那家公司在電子學領(lǐng)域中占據(jù)的領(lǐng)先地位。
4. The tyrant's domination was challenged by the rebels.
   暴君的統(tǒng)治受到了反叛者的挑戰(zhàn)。

chal.leng.ing

adj.（形容詞）
Calling for full use of one`s abilities or resources in a difficult but stimulating effort:
挑戰(zhàn)性的：在困難但振奮人心的+事件中要求充分運用某人的能力或才智的：
例句：
a challenging course of study; a challenging role for an inexperienced performer.
一門挑戰(zhàn)性的課程；給一個無經(jīng)驗的演員一個挑戰(zhàn)性的角色

Absorbing; intriguing:
引起興趣的；令人深思的：
例句：
a challenging idea.
一個吸引人的觀點