First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the Environmental Revolution. It sets the stage for the discussion about how companies have changed their business practices. It does not refer to any previous information, making it independent. Why other lines are not chosen? Paragraph 2 starts with "In the 1960s and 1970," which refers to a specific time and is not independent. Paragraph 3 starts with "Then," which is a conjunction and does not stand alone. Paragraph 4 starts with "In the United States," which also refers to a specific place and is not independent. Paragraph 5 starts with "Today," which is a time reference and does not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion. It shows how companies have changed their behavior after the problems discussed earlier. It reflects the overarching theme of responsibility towards the environment.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it shows the past state of corporations. The phrase "In the 1960s and 1970" gives a time frame that follows the introduction of the Environmental Revolution.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically because it explains what happened after the denial of corporations. The word "Then" shows a cause and effect relationship between the denial and the problems that arose.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it gives specific examples of the ecological problems mentioned. This is a broader to specific strategy, where the general statement is followed by specific examples.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 follows Paragraph 4 because it shows the result of the ecological problems. The word "Today" indicates a change in attitude from the past problems to the current responsibility of companies.