First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the text. It clearly states that science and technology are important in today's society. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with "But" which is a conjunction, so it cannot be independent. Paragraph 3 starts with "Whether" which makes it dependent on previous context. Paragraph 4 uses "Human existence" but does not introduce the topic; it assumes prior knowledge.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the main point of the text. It shows the importance of science in many areas of life. This follows the Summary Style rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the idea of the importance of science and technology. This follows the Logical Order rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it questions the impact of science and technology on human existence. This follows the Cause and Effect Relationship rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it provides evidence for the argument made in Paragraph 3. This follows the Logical Order rule.