1、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。

2、pull up

（车或驾车者）减速停下

The cab pulled up and the driver jumped out.

出租车减速停下，司机跳了出来。

（使）突然停下；（使）猛地停住

Suddenly, he pulled up sharply in his stride, and fell to the floor.

突然，原本大步流星的他猛地停住了脚步，倒在了地上。

She recognized at the same instant Rachel's presence. It pulled her up short.

雷切尔一出现她就认出她来了，随即停下了手中的活儿。

提高；改进

We had a very good mathematics mistress who pulled me up.

我们有个很出色的女数学老师，她帮我提高了水平。

He was made redundant and now he's trying to pull himself up again.

他之前作为冗员被裁，现在他正试图再一次奋发图强。