1. Take a small amount of samples from A to H, add 2,4-dinitrophenylhydrazine, and the precipitates are D, E and H (recorded as a group); A, B, C, F, G without precipitation (recorded as two groups).
2. Take a small amount of substances in each group and add iodine solution and 10%NaOH to generate yellow precipitate, D and E; No yellow precipitate is H, take a little D and E, and add Fehling reagent. The one with brick red precipitate is E, and the one without precipitate is D.
3. Take a small amount of substances from each group and add saturated solution of bromine. White precipitate is G, and non-precipitate is A, B, C and F. Add 5%NaHCO3 to A, B, C and F, and release carbon dioxide gas as B, and non-generate gas as A, C and F. Take A, C and F, add iodine solution and 10%NaOH, and yellow precipitate as F, and yellow precipitate as A and C. Take A. The gas (carbon dioxide) that can make blue litmus test paper turn red is C, and the gas without it is A..