20. justification. (1) demonstrates the harm of unprofessionalism and demonstrates the argument from the opposite side. (The meaning is close) (1 min)

2 1. Not so good. (1 min) Because the author demonstrates from both positive and negative aspects, if one is removed, the content of the argument will be incomplete and the process of the argument will not be rigorous. ( 1)

22. Example: Street sweepers get up early every day, greedy for the dark, not afraid of being dirty and tired, and clean the streets cleanly. They don't dislike this bitter and tiring occupation, and always do their own jobs in a down-to-earth manner. This kind of professionalism of doing one thing and loving another deserves our respect. (For example, 1 minute is correct, and 1 minute is reasonable for evaluation).