He loves sport and wants to challenge himself in triathlon—a sports competition in which people swim 4 kilometers, bike 180 kilometers and run 42 kilometers.

他热爱运动，并且想在铁人三项中挑战自己，而铁人三项是一项包含4公里游泳、180公里骑行和42公里跑步的运动比赛。

youdao

Try to work for someone who’ll challenge your powers.You’ll learn more in a year than 4 years of college。

尝试为那些会对你的个人能力形成挑战的人工作。 你会在一年的时间学习到超过大学四年的东西。

youdao

A 10 is a book that might even pose a challenge for us, and a 4 is probably around the easiest book we would recommend.

一本难度为10的书即使对我们而言也是一个挑战，而一本难度为4的大概会是我们推荐的书中最容易的。

youdao

Araafa, fourth in the Newmarket classic, fought off a late challenge from the 4-7 favourite.

BBC: SPORT | Other Sport... | Horse Racing | Araafa upsets odds for Irish win

Ben and some friends started a company, Inventech Enterprises, LLC, to try to bring to manufacture a number of the prototypes developed for the AbilityOne Design Challenge over the past 4 years.

FORBES: Innovation For Accessibility

According to local site Vegas Chatter, Cabo Wabo in Planet Hollywood has an 8-pound, 20-topping nacho challenge, while Diablo's Cantina in Monte Carlo has both a spicy 20-piece "Death Wing" and 4-pound burrito challenge.

FORBES: You vs. Food