牛奶营养丰富,含有人体所需要的多种营养素,尤其是其中所含的维生素A极为丰富,随着经济生活水平的提高,电视机基本普及,人们收看电视通常在较暗的环境下,人的眼睛视紫质消耗较多,容易造成维生素A的缺乏,引起夜盲症、角膜软化、角 Milk rich in nutrients, containing the human body needs a variety of nutrients, especially the vitamin A contained therein is extremely rich, with the improvement of economic living standards, the basic popularity of television, people watch TV is usually in the dark environment, the human Eyes as rhodopsin consumption more likely to cause the lack of vitamin A, causing night blindness, corneal softening, angle