A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of machines. It gives a broad overview of what all machines have. It does not refer to any previous information. Why other lines are not chosen? Paragraph 2 starts with 'Machines that receive...' which is not general. It uses 'that' which refers back to machines. Paragraph 3 starts with 'Windmills...' which is specific and does not stand alone. Paragraph 4 starts with 'In these prime movers...' which uses 'these' and refers back to something not yet introduced.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about prime movers. It gives details about how they work and what they produce.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the topic of machines. It explains what kind of machines are discussed, showing a logical order.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives examples of the machines mentioned in Paragraph 2. This shows a broader to specific strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains more about the prime movers listed in Paragraph 3. It shows how these machines work, which is a logical order.