First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of library classification. It gives a clear overview of what library classification is. It does not use any words that need prior context. Why other lines are not chosen? Paragraph 2 starts with 'While', which is a conjunction. This means it cannot stand alone. Paragraph 3 starts with 'Arranging', which is not a general statement and does not introduce the main topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the ideas about classification and arrangement. It gives a final thought on how arranging things helps to control information.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains more about classification. It uses the connector 'While' to show that it is giving additional information about the topic introduced in Paragraph 1.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it talks about the idea of arranging things. It continues the topic of classification by explaining how arranging similar things helps control information.