1. 挑战;难题
    A challenge is something new and difficult which requires great effort and determination.

    e.g. I like a big challenge and they don't come much bigger than this...
           我喜欢大的挑战，而所有挑战中再没有比这更大的了。
    e.g. The new government's first challenge is the economy.
           新政府面临的第一个难题是经济问题。

2. (成功地)应对挑战，迎接挑战
    If someone rises to the challenge, they act in response to a difficult situation which is new to them and are successful.

challenge

    e.g. The new Germany must rise to the challenge of its enhanced responsibilities...
           一个崭新的德国必须迎接挑战，承担更多的责任。
    e.g. They rose to the challenge of entertaining 80 schoolchildren for an afternoon.
           他们一个下午成功接待了80名学童。

3. (对真实性、价值、权威等提出的)怀疑，质疑
    A challenge to something is a questioning of its truth or value. A challenge to someone is a questioning of their authority.

    e.g. The demonstrators have now made a direct challenge to the authority of the government.
           示威者现在直接对政府的权威发出了质疑。

4. 怀疑，质疑(真实性、价值、权威等)
    If you challenge ideas or people, you question their truth, value, or authority.

    e.g. Democratic leaders have challenged the president to sign the bill...
           民主党领袖对总统签署这项法案提出了质疑。
    e.g. The move was immediately challenged by two of the republics...
           此项动议立即遭到其中两个共和国的反对。

5. 挑战；向…下战书
    If you challenge someone, you invite them to fight or compete with you in some way.

    e.g. A mum slashed a neighbour's car tyre and challenged her to a fight after their daughters fell out...
           两家的女儿吵起来后，一个妈妈划破了邻居的车胎，说要和她较量较量。
    e.g. He left a note at the scene of the crime, challenging detectives to catch him...
           他在犯罪现场留了个条儿，向警探挑衅。

6. (警卫)盘问，查问
    If someone is challenged by a guard, they are ordered to stop and say who they are or why they are there.

    e.g. The men apparently opened fire after they were challenged by a patrol.
           显然，那些人是在受到一支巡逻队的盘问后开的火。

7. see also: challenged
    see also: challenging