1、effective

有效的;能產生預期效果的

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

該項目著眼于我們如何能夠更加有效地鼓勵學生參與教師培訓。

Simple antibiotics are effective against this organism.

一般的抗生素能夠有效對抗這種微生物。

實際的;事實上的

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

自從安全部隊撤離后，他們實際上控制了該地區。

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

原本會使他們最熱門的一條短途旅游線路的費用出現實質性上漲的調整

（法律、協議等）生效的，起作用的

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

新規定將在幾天后生效。

2、challenge

挑戰;難題

I like a big challenge and they don't come much bigger than this.

我喜歡大的挑戰，而所有挑戰中再沒有比這更大的了。

The new government's first challenge is the economy.

新政府面臨的第一個難題是經濟問題。

(成功地)應對挑戰，迎接挑戰

The new Germany must rise to the challenge of its enhanced responsibilities.

一個嶄新的德國必須迎接挑戰，承擔更多的責任。

They rose to the challenge of entertaining 80 schoolchildren for an afternoon.

他們一個下午成功接待了80名學童。

懷疑，質疑(真實性、價值、權威等)

Democratic leaders have challenged the president to sign the bill.

民主黨領袖對總統簽署這項法案提出了質疑。

The move was immediately challenged by two of the republics.

此項動議立即遭到其中兩個共和國的反對。