Sandwiches and sandwiches are transliterated through the English word sandwich. Sandwich is a typical western food, made of two pieces of bread with a few pieces of meat, cheese and various seasonings. It is easy to eat and popular in western countries.
Heat refers to the energy transferred by the temperature difference between the thermal system and the outside world. Heat is a process quantity, so heat can only be said to be "absorbed" and "released". You can't say "contain" or "have". This transfer process is called heat exchange or heat transfer. The unit of heat is joule (j). All life activities of human body need energy, such as synthetic reaction of substance metabolism, muscle contraction, gland secretion and so on. And these energies mainly come from food. Nutrients contained in animal and plant foods can be divided into five categories: carbohydrates, lipids, protein, minerals and vitamins, and water is six categories. Among them, carbohydrates, fats and protein can release energy through in vivo oxidation. These three are collectively referred to as "productivity nutrients" or "heat sources".