Listen to part of a lecture in an environmental science class. Professor: Today we're going to discuss the concept of 'urban heat islands.' As you know, cities tend to be warmer than surrounding rural areas. This is because materials like concrete and asphalt absorb and retain heat, while vegetation, which provides shade and releases moisture, is scarce. But there are potential solutions. One is to increase the albedo of surfaces by painting roofs white or using reflective materials. This can lower surface temperatures significantly. Another approach is to plant more trees and create green roofs, which not only provide shade but also cool the air through evapotranspiration. However, these solutions vary in effectiveness. For instance, green roofs are most beneficial in hot, dry climates, while cool roofs might be more effective in humid regions. Additionally, the placement of trees matters—they need to be strategically located to shade buildings during peak sun hours. So, while there's no one-size-fits-all fix, a combination of strategies tailored to local conditions can mitigate the heat island effect.
❓ 문제 What is the main purpose of the lecture?
A. To explain why cities are warmer than rural areas
B. To compare the effectiveness of different solutions to urban heat islands
C. To argue that green roofs are better than cool roofs
D. To describe the process of evapotranspiration
✅ 정답
To compare the effectiveness of different 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