Read the summary of the passage. One key idea is missing When ice and snow form on a plane, a deicing process must be done. The process starts with a glycol mixture that is sprayed over the entire plane. The process must be done quickly to prevent new ice from forming. Sometimes an anti-icing mixture also made of glycol is used. While new ways of protecting a plane from ice are being researched, glycol compounds are the only way to do it right now. Which key idea is missing?​