1、effective

有效的;能产生预期效果的

The project looks at how we could be more effective in encouraging students to enter teacher training.

该项目着眼于我们如何能够更加有效地鼓励学生参与教师培训。

Simple antibiotics are effective against this organism.

一般的抗生素能够有效对抗这种微生物。

实际的;事实上的

They have had effective control of the area since the security forces left.

自从安全部队撤离后，他们实际上控制了该地区。

a restructuring that would have resulted in an effective increase on one of their most popular excursion fares.

原本会使他们最热门的一条短途旅游线路的费用出现实质性上涨的调整

（法律、协议等）生效的，起作用的

The new rules will become effective in the next few days.

新规定将在几天后生效。

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。