Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'urban heat islands,' a phenomenon where cities are significantly warmer than surrounding rural areas. This occurs because materials like concrete and asphalt absorb and retain heat during the day and release it at night. Additionally, lack of vegetation reduces shade and evapotranspiration, which naturally cools the air. One surprising factor is that the heat generated by human activities—such as transportation, industrial processes, and even air conditioning—contributes to the effect. However, solutions are emerging. For example, green roofs, which are covered with plants, can lower rooftop temperatures by up to 40 degrees Celsius. Another approach is using reflective or 'cool' pavement materials that bounce back more sunlight. But these measures require upfront investment. The question is, are they cost-effective in the long run? Studies suggest that reducing peak electricity demand during hot summers can save millions of dollars, not to mention the health benefits from lower heat-related illnesses. So, while initial costs are high, the long-term savings and environmental gains make them worthwhile.
❓ 質問 What is the main topic of the lecture?
A. A. The causes and potential solutions to urban heat islands.
B. B. The economic costs of installing green roofs in cities.
C. C. How transportation affects global warming.
D. D. The differences between urban and rural weather patterns.
✅ 正解
A. The causes and potential solutions to urban heat islands.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word
