Wearing the number 21 is a tribute to my brother-in-law who taught me to play basketball when I was 14.

我穿21号球衣是因为我的姐夫，是他在我14岁的时候教会我打篮球的。

youdao

For Milan's number 21 these last 10 months have been unforgettable.

对于米兰的21号来说，这10个月是难以忘记的。

youdao

Rare earth metal: Any of a large class of chemical elements including scandium (atomic number 21), yttrium (39), and the 15 elements from 57 (lanthanum) to 71.

稀土金属：一个化学元素大家族中的任何一种，包括钪(原子序21)、钇(原子序39)以及从57号元素(镧)到71号元素。

youdao

Rare earth metal: Any of a large class of chemical elements including scandium (atomic number 21), yttrium (39), and the 15 elements from 57 (lanthanum) to 71.

稀土金属：一个化学元素大家族中的任何一种，包括钪(原子序21)、钇(原子序39)以及从57号元素(镧)到71号元素。

youdao