First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the text. It talks about how electronic systems help control joints and how bionic limbs help disabled people. This is a broad overview of the subject. Why other lines are not chosen? Paragraph 2 starts with "When it comes to competitive sport," which makes it dependent on prior context. Paragraph 3 starts with "This is in order to ensure," which also needs context. Paragraph 4 starts with "Whether this will change," which is not a general statement and needs more information.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion. It talks about the debate on whether the rules will change. This gives a final thought on the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it talks about a problem with the technology mentioned in Paragraph 1. The word "however" shows a contrast between the benefits of bionic limbs and the issues in competitive sports.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 explains why the technology needs to be controlled. It follows logically after Paragraph 2 because it gives a reason for the problem mentioned. The phrase "in order to ensure" shows the purpose of the technology.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it discusses the future of the technology. It shows that there is a debate about whether the rules will change. The phrase "is a point of contention" indicates that there are different opinions.