twenty-one
14, 21 and 28 are all multiples of 7.───14、21和28都是7的倍数。
The product of 21 and 16 is 336.───21和16的乘积是336。
I'm a teacher with 21 years' experience.───我是一个有21年经验的教师。
The graph below the images tracks the surface elevation of Devils Lake from the late nineteenth through the early twenty-first centuries.───图像下面的图表记录了魔鬼湖在19世纪末到21世纪初的水面高度的变化轨迹。
An employee attends to a light fitting in an unoccupied floor of "The Peak" office complex in London, UK, on Thursday, Jan.───如雇员参加的灯具在一个“山顶”，在英国伦敦，周四复杂的办公室空置楼，2010年1月21日。
Although a fashionable person of the 21st century can still be described as hip, they would not be referred to as a hippie.───尽管21世纪的时尚人士仍旧可以被形容为“时髦的”，但他们不会被当作一个嬉皮。
The classmates, 21st century belongs to us, let us always ready to meet new challenges, create the new brilliance!───同学们，21世纪属于我们，让我们时刻准备着迎接新的挑战，创造新的辉煌！
At the age of 21 she was dating 3 men a day. The man of her dreams works only 2 minutes from her home.───21岁的时候她甚至一天约会3个男人。
They then went back and eliminated 21 of the trials, leaving only the "low-bias" ones. This was the next level of quality standard.───然后他们返回将其中的21个试验结果排除，保留低偏差的一组，这是第二水平的质量标准。