1N-COUNT (生物体生长所需的)微量元素 A trace element is a chemical element such as iron or zinc that occurs in very small amounts in living things and is necessary for normal growth and development. (生物体生长所需的)微量元素
2N-COUNT (金属或其他物质中的)痕量元素，微量元素 A trace element is a very small amount of a chemical element that is found in a metal or other substance. (金属或其他物质中的)痕量元素，微量元素