challenge/ 'tʃælɪnʤ /

1.noun [c/u] 
(hard task) 挑战

2.noun
(to authority,ideas) 异议

3.noun
(to rival,competitor) 挑战

4.vt.[+authority] [ right] [ idea] 
质疑

5.vt.[+rival] [ competitor] 
向…挑战

to rise to the challenge
迎接挑战
to challenge sb to do sth
向某人提出挑战做某事
to challenge sb to a fight/game
挑战某人打架/比赛