A wise man said: "To know the melting point of this substance, you need to measure it strictly. First take an appropriate amount of this substance, put it in a special container, and use a precise instrument to control the temperature, slowly heat up, and observe the change of its state. When the substance gradually turns from solid to liquid, the temperature at this time is the melting point of this substance. If you measure the melting point of Hf, follow this path and operate carefully, you can get an accurate number, so that everyone can solve the confusion."