A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It tells us that the Wright brothers' flight is very important. This is a general statement that does not need other sentences for context. It does not use any pronouns or definite articles that refer to previous ideas. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'In 1903,' which needs more context. Paragraph 3 uses 'this invention,' which refers back to something not yet mentioned. Paragraph 4 starts with 'Without the Wright flyer,' which also needs prior context.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion. It gives specific examples of how the Wright flyer has changed our lives. It shows the overall impact of the invention, which is a good way to end the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives an example of the Wright brothers' flight. This is a 'Topic Example' connection. The first paragraph talks about the importance of the flight, and the second paragraph explains what that flight was.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about the impact of the invention. This is a 'Broader to Specific Strategy.' The second paragraph gives details about the flight, and the third paragraph explains how it changed many things.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it gives specific examples of how the invention changed things. This is a 'General to Specific' connection. The third paragraph talks about changes in general, and the fourth paragraph gives specific examples.