Second, it was first seen in Oracle Bone Inscriptions, and its original meaning was the poles of heaven and earth separated by chaos, and later it was extended to the sum of one plus one, ranking second, disloyal and so on. Related words: half-hearted, silent, second, the same, unique and so on.
2. Explanation 2: 1.2 is a natural number and a positive integer between 1 and 3.
There are many mathematical properties. If a number is divisible by 2, it is even, and vice versa. 2 is the smallest prime number (also called prime number),
1 and 2 have only two factors and are rational numbers. 2.2 is also a network language, which means "idiot, idiot".