请听下面5段对话，选出最佳选项。 1.What are the two speakers talking about? A. A method. B. A theory. C. A rule. 2. What does the woman mean? A. She agrees with the man. B. Life cannot exist without sunlight. C. Air is fundamental to all living things. 3. Why does the woman mention her dinner guests? A. To invite the man to join them. B. To ask the man to help cook. C. To suggest politely that the man leave. 4. What’s the two speakers’ opinion about the solar energy? A. It’s useful but costs a lot. B. It’s convenient and inexpensive. C. It’s green and can help save money. 5. What can we learn from the conversation? A. The man is not interested in astronomy. B. The two speakers are reading a book. C. The woman is studying astronomy.