1、ultimate

最后的；最终的

He said it is still not possible to predict the ultimate outcome.

他说现在还无法预料最终的结局。

The ultimate aim is to expand the network further.

最终目的是为了进一步拓展该网络。

最根本的；最基础的；最原始的

Plants are the ultimate source of all foodstuffs.

植物是所有食物的最根本来源。

The ultimate cause of what's happened seems to have been the advertising campaign.

出事的最根本原因似乎在于那场广告宣传活动。

最重要的；最强大的；至高的

the ultimate power of the central government.

中央政府的至高权力

Of course, the ultimate authority remained the presidency.

当然，拥有最高权力者依然是总统。

2、challenge

挑战;难题

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。

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。

(成功地)应对挑战，迎接挑战

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。

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。

怀疑，质疑(真实性、价值、权威等)

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。

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。