Final answer:
The phrase "handsome building" can be changed when paraphrasing, as it's descriptive and not a fixed term or proper noun. Other phrases like "within 18 months", "plan 'K'", and "William Lamb" are likely specific and would retain their original form in a paraphrase.
Step-by-step explanation:
When paraphrasing the phrase "handsome building" could be replaced with different words to maintain the original meaning but use alternate language. This could be rephrased as "attractive structure" or "elegant edifice" depending on the context. The phrases "within 18 months", "plan 'K'", and "William Lamb" are more likely to be specific, fixed terms or proper nouns that would not change in a paraphrase because they refer to precise details or names that would lose meaning if altered. Paraphrasing typically involves rewording and restructuring while keeping the original meaning intact, especially in the context of academic writing or summarizing literature.