First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the construction process. It uses the rule of Topic Sentence, as it starts with 'Initially,' which shows it is the beginning of the process. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone as the first sentence. For example, Paragraph 2 starts with 'After,' which shows it needs prior context. Paragraph 3 starts with 'Upon,' which also needs earlier information. Paragraph 4 starts with 'The wings,' which assumes knowledge of wings. Paragraph 5 starts with 'Upon completion,' which indicates it follows another action.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the construction process. It uses the rule of Conclusive Words, as it talks about the 'final step,' which indicates it is the end of the process.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it uses the Connector strategy. The word 'After' shows that it follows the first step of construction, which is the cockpit assembly.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 using the Logical Order strategy. The phrase 'Following the fuselage assembly' shows the next step after the fuselage is built.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 through the Object Subject Strategy. The subject of Paragraph 3 is the wings, and Paragraph 4 continues with the wings being attached to the fuselage.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 using the Chronological Order strategy. The phrase 'Upon completion of the wings' shows it is the final step after the wings are attached.