A, when titrated with NaOH solution, the ionic equation of the reaction is H-+OH+=H2O. Incorrect acetic acid cannot be completely ionized. B, vinegar samples need to be diluted by a certain multiple before titration. C, vinegar can be titrated with NaOH solution, but phenolphthalein or methyl orange can be used as indicator. D. If the measured amount of substances in this brand of vinegar is 0.75mol/L, then the total acid content of vinegar is 4.5g/ 100mL, and the correct answer is: 0.75 mol/L = 0.75 * 60g/L = 45g/L = 4.5g/100 ml.