1, when it is a pure number, it has no meaning and is a natural number;

2. When it is in kind, it means that the quantity of this kind of thing is zero, or there is no such thing;

3. When the temperature is 0℃, it does not mean that there is no temperature;

4. When it is time, a means 0: 00 a.m. and b means the time period is 0 (minutes, seconds, etc.). );

5. When it is speed, it means that the object is at rest;

6. When it is height, it means that the height measured from this datum point or surface is 0 meters (decimeter, centimeter, etc. );