Chemistry: melon seeds, walnuts, peanuts and other substances are rich in oil, so it is not easy to joke if you eat more. A simple way to verify whether it contains grease is

Solution: Method 1: Because oil stains will remain on the items soaked in oil and grease, the answer is: put melon seeds, walnuts, peanuts and other substances on a piece of white paper, press hard, and oil stains will appear on the paper.

Method 2: Because oil is less dense than water and insoluble in water, it can be broken and added with water. So the answer is: break melon seeds, walnuts, peanuts and other substances and add water, and oil drops appear on the water surface.