(1) Green food refers to the general name of safe, high-quality and nutritious food which is planted and bred without pollution, applied with organic fertilizer, processed and produced under standardized environment, production technology and hygiene standards, and recognized by authoritative organizations with special signs for eating.

(2) Green food is divided into Grade A and Grade AA: the logo and font of Grade A green food are white, and the background color is green; Class A green food is allowed to use limited chemical synthetic substances in the production process; The symbol of green food consists of the sun above, the flower buds in the middle and the green leaves below. The logo and font of AA grade green food are green and the background color is white. AA grade green food is not allowed to use any harmful chemical synthetic substances in the production process. As can be seen from the figure, "Yili pure milk" belongs to grade A green food, and limited chemical synthetic substances are allowed to be used in the production process of grade AA green food.

(3) Developing "green food" is an important measure to improve the quality of human life and maintain health.

Therefore, the answer is: (1) security; High quality; Nutrition;

(2) Yes; Allow;

(3) improve the quality of human life and maintain a healthy level;