One kilogram is 500 grams and 500 milliliters. Jin is the unit of weight, milliliter and liter are unit of volume, and an equal sign cannot be used between two different units. When the liquid density unit is 1g/ml, gold = 500ml/ liquid density. Only when the density and mass of matter are known can the volume be calculated. The unit of measurement is the agreed definition and specific quantity used to express the size of the same quantity compared with it. The unit of measurement is named and symbolized by the agreement. For some quantities with the same dimension, even if they are not the same quantity, their units can have the same name and symbol.