双数的英文：
even number

参考例句：

Ancient greek had the dual but it has merged with the plural form in modern greek.
古希腊语中有双数，但在现代希腊语中已同复数形式合并在一起了。

And Kwaio has not just singular and plural but dual and paucal too.
瓜依沃语中不光有单数和复数，还有双数和若干的概念。

number是什么意思：
n. 数；号码；算数
v. 给…编号；计算，数

The number was fifty.
该数字为五十。

There is safety in numbers
人多势众

It was an irrational number.
这是一个无理数。

Which number on the card is a prime number?
在卡片上哪一个数字是最初的数字？

The number raised to the logarithm of a designated number in order to produce that designated number.
被升到指定数字的对数上的数量,是为了得到那被指定的数目。