Colombia's army and air force quickly found the kidnappers and forced them to release 21 of the hostages.

哥伦比亚陆军和空军很快找到了这些劫匪，并迫使他们释放了期中的21名人质。

youdao

Yang Liwei, then a lieutenant-colonel in the Chinese air force, spent 21 hours in space.

当时还是中国空军中校的宇航员杨利伟在太空中度过了21个小时。

youdao

Lawyers have been torturing the term as 21 states over the past three years of budget pain considered whether and how to force retailers (most notably Amazon) to collect sales tax.

在再过去的三年中，有21个州一边考虑支出预算，一边想着怎么怎样迫使零售商 （特别是亚马逊）缴纳销售税。 于是律师们一直在折磨着“关系”这个术语。

youdao

Chapman's father, Wilbur -- retired from the Air Force after 21 years -- said his son called them Christmas morning on a satellite phone, saying he was sorry not to be with his wife and children.

CNN: Killed soldier devoted to family, country, parents say

But fewer people remained out of the labour force altogether: 21.1% of the working-age population was neither in work nor looking for a job, the lowest rate since 1992.

ECONOMIST: Overview

Data from Elstat, the country's statistics agency, showed that the number of jobless climbed to 1.08 million, or 21.9% of the work force, up from a revised 21.4% rate in February.

WSJ: Greek Political Debate Turns Violent