A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the Terracotta Army. It gives a clear overview of what the text will be about. It does not use any words that need prior context. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with "However," which is a conjunction. Paragraph 3 uses "the" which assumes prior knowledge. Paragraph 4 also uses "the" and does not introduce the topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas. It gives a final thought about the importance of the Terracotta Army. It summarizes the text and reflects the main theme.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the topic of the Terracotta Army. It uses the phrase "This vast collection" to refer back to the Terracotta Army. This is a clear example of the Noun Pronoun Rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it introduces a new idea about the techniques used to create the sculptures. The word "However" shows a contrast to the previous information, which is a Connector strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it provides a conclusion about the significance of the Terracotta Army. It summarizes the importance of the sculptures, showing a logical order from discussing techniques to discussing their value.