A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of advertising. It gives a clear overview of how advertising is done today. It does not refer to any previous information, so it stands alone. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. For example, Paragraph 2 starts with 'Moreover,' which is a conjunction. Paragraph 3 uses 'Some governments,' which is not a general statement. Paragraph 4 also starts with 'But,' which is a conjunction. Therefore, they cannot be the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the main idea of the previous paragraphs. It wraps up the discussion about advertising and why it is not common. It uses the word 'Moreover' to add final thoughts.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 using the Contrast rule. The word 'But' shows a contrast to the idea of advertising being common. It suggests that even though advertising is done in this way, it is not common everywhere.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 using the Logical Order rule. It explains why advertising is not common. It gives a reason that some governments do not support advertising.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 using the Connector strategy. The word 'Moreover' adds more information about why some governments discourage advertising. It shows that they think it wastes resources.