Narrator: Listen to part of a lecture in an environmental science class. Professor: So today we're talking about urban heat islands. Now, cities tend to be warmer than surrounding rural areas. Why is that? Well, one major factor is the replacement of natural surfaces with asphalt and concrete. These materials absorb and retain heat during the day and release it slowly at night. Another factor is the lack of vegetation. Trees and plants provide shade and cool the air through a process called evapotranspiration, where water evaporates from leaves, taking heat with it. Also, human activities—like driving cars, running air conditioners, and industrial processes—generate waste heat. Interestingly, the heat island effect can vary within a city. Dense downtown areas with tall buildings and narrow streets trap heat, while parks and green spaces can create cooler pockets. So, what can we do about it? One solution is green roofs—planting vegetation on rooftops. Not only do they insulate buildings, reducing energy use, but they also help cool the surrounding air. Another approach is using reflective or 'cool' pavements that bounce sunlight back instead of absorbing it. But these solutions require investment and policy changes. Any questions?
❓ 题目 According to the professor, what is one reason why cities are warmer than rural areas?
A. A. Rural areas have more reflective pavements.
B. B. Urban materials like concrete absorb and retain heat.
C. C. Cities have more trees that trap heat.
D. D. Human activities in rural areas generate more waste heat.
✅ 正确答案
B. Urban materials like concrete absorb and retain heat.