Another thing to consider is the use of technical terms. For example, "PDF format" in the first part is a proper noun? No, "PDF" is a known abbreviation, but it's a technical term here. Since the user said "don't touch proper nouns", maybe "PDF" should remain as is. Let me verify if "PDF" is considered a proper noun. Typically, PDF is an acronym for Portable Document Format, so it's a proper noun by convention. So I should leave "PDF" unchanged.
First, I need to go through the text line by line. Starting with the first part about Project Gutenberg. The original sentences are about Project Gutenberg offering public domain Superman comics. I need to replace each word (except proper nouns) with three synonyms or related terms. Words like "offers" could become "provides|features|includes", "limited" might be "restricted|modest|small", and so on. Proper nouns like Project Gutenberg and Superman should stay as they are. superman comics pdf
Also, the user said to not change proper nouns. So words like Comixology, Amazon Kindle, DC Comics Digital, Project Gutenberg should stay the same. So in the sections about each platform, the names are kept, but the descriptions are spun. Another thing to consider is the use of technical terms