有任何疑问或需要帮助，请通过邮件或社交平台联系我们。您的反馈是我们改进的重要动力。Oxygen is considered the most ample factor in Earth's crust, making up Practically 50 % in the Earth's crust in the form of varied oxides which include water, carbon dioxide, iron oxides and silicates.[6] It is the third-most c