【第1句】：一篇关于维生素A的英语文章

Vitamin A is an essential human nutrient. Its important part is the retinyl group, which can be found not in a single compound, but in several forms. In foods of animal origin, the major form of vitamin A is an alcohol (retinol), but can also exist as an aldehyde (retinal), or as an acid (retinoic acid). Precursors to the vitamin (provitamins) are present in foods of plant origin as some of the members of the carotenoid family of compounds.[1]

All forms of vitamin A have a Beta-ionone ring to which an isoprenoid chain is attached. This structure is essential for vitamin activity.[1] The orange pigment of carrot - Beta-carotene - can be represented as two connected retinyl groups. Retinyl group, being attached to a protein, is the only primary light absorber in visual perception, and the compound name is related to retina of eye.

Vitamin A may be found in various forms:

retinol, the animal form of vitamin A, is a yellow, fat-soluble, vitamin with importance in vision and bone growth. Since the alcohol form is unstable, the vitamin is usually produced and administered in a form of retinyl acetate or palmitate.

other retinoids, a class of chemical compounds that are related chemically to vitamin A, are used in medicine.

【第2句】：维生素的英语翻译 维生素用英语怎么说

词典释义vitamine 维生素（一般情况下用这个或者省略末尾的e）vitamin(e) 维生素；维他命auxohormome维生素nutramin(e)[医] 维生素（别名）citrin 维生素P，柠檬素双语例句 【第1句】：新鲜水果和蔬菜提供植物纤维素和维生素。

Fresh fruit and vegetables provide fibre and vitamins. 【第2句】：我建议你在日常饮食中补充些维生素E和维生素A。I suggest supplementing your diet with vitamins E and A.满意请采纳❤。

【第3句】：用英语翻译下列句子

【第1句】： Vegetables contain many vitamins.

【第2句】： Many people took part in the

activities, including some of the students

【第3句】： Students can have access to the library.

【第4句】： ThE reference book is designed for college

students

【第5句】： Students are not permitted to play mobile phone in

class.

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【第4句】：应英文回答

vitamin:

Any of various fat-soluble or water-soluble organic substances essential in minute amounts for normal growth and activity of the body and obtained naturally from plant and animal foods.

维生素：

各种脂溶性或水溶性生命物质之一，少量的这种物质对生命体的生长和活动至关重要，通常从植物食物中取得