First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic, which is London. It gives a broad overview of the city and its importance. It does not use any words that need prior context. Why other lines are not chosen? Paragraph 2 starts with 'It has', which makes it dependent on prior information. Paragraph 3 starts with 'Another landmark', which also needs context. Paragraph 4 starts with 'It is known', which refers back to something not yet mentioned. Paragraph 5 starts with 'It has', which is also dependent.

Concluding sentence: Why this is the last line? This paragraph is the last because it provides specific information about One Canada Square, which wraps up the discussion about landmarks in London. It gives a clear conclusion to the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because Paragraph 2 gives more details about London’s skyline after introducing the city in Paragraph 1. This follows the Broader to Specific Strategy.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because Paragraph 3 continues to talk about skyscrapers in London after mentioning the Swiss Re Tower in Paragraph 2. This follows the Logical Order strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because Paragraph 4 introduces a new topic about newspapers in London after discussing buildings in Paragraph 3. This follows the Topical Order strategy.
• Pair 4 (Paragraph 4 → Paragraph 5): This pair connects because Paragraph 5 gives specific details about One Canada Square, which is mentioned in Paragraph 4. This follows the Broader to Specific Strategy.