A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It gives a broad overview of the situation in Britain after World War II. It does not refer to any previous information. Why other lines are not chosen? Paragraph 2 starts with "The British government" which uses a definite article and assumes prior knowledge. Paragraph 3 starts with "Most found jobs" which also uses a definite article. Paragraph 4 starts with "Each year" which is a specific time reference and does not introduce the topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion. It summarizes the outcomes of the migration and gives a clear conclusion about the people who came to Britain.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because the second paragraph explains what the government did in response to the lack of workers. It shows a logical order of cause and effect.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because the second paragraph shows the result of the first. It explains that many people came to Britain because of the job advertisements.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because the fourth paragraph explains what happened after people migrated. It shows the logical order of migration leading to finding jobs.
• Pair 4 (Paragraph 4 → Paragraph 5): This pair connects because the fifth paragraph explains the outcomes of finding jobs. It shows the contrast between those who stayed and those who did not.