(1) The Balanced Diet Pagoda divides food into six groups, which shows how much people need for various nutrients every day. The bottom of the Balanced Diet Pagoda is the widest layer, which shows that the food in this layer is the main part of the dietary structure, and the amount decreases from the bottom to the top. This difference shows that people need different nutrients.

(2) The bottom of the balanced diet pagoda contains cereals, such as rice, oats, noodles, etc.

(3) The amount of exercise, one's physique, growth and development period, etc. all affect one's nutrient intake. If the amount of exercise is large and one is in the growth and development period, the intake of each group of food should be more.

(4) Because other groups of food contain fat and sugar, the extra intake of sugar and fat should be limited, which can prevent obesity, hypertension, arteriosclerosis and other diseases. This means that people should eat this kind of food in moderation.

Therefore, the answer is: (1) six groups;

(2) cereals;

(3) People's daily demand for various substances is related to the amount of exercise, personal physique and growth and development period;

(4) People should eat this kind of food in moderation.