Narrator: Listen to part of a lecture in an environmental science class.
Professor: Today we’re going to talk about urban heat islands, and one surprising factor that contributes to them: the color of rooftops. Dark roofs absorb more solar radiation, converting it into heat, which raises the temperature of the surrounding air. In contrast, cool roofs—painted white or another reflective color—reflect sunlight and stay cooler. But here’s the interesting part: the benefits of cool roofs go beyond just reducing the need for air conditioning. Studies have shown that in some cities, widespread adoption of cool roofs could lower local air temperatures by up to 2 degrees Celsius, which in turn reduces smog formation, because heat accelerates the chemical reactions that create ground-level ozone. However, there’s a trade-off. In colder climates, the same reflective roofs can increase heating costs during winter, since they reduce the natural solar warming of buildings. So, urban planners must weigh the seasonal and regional impacts before recommending a blanket policy.
❓ Pregunta What is the main point the professor makes about cool roofs?
A. A. They are most effective in reducing smog in all climates.
B. B. They have both benefits and drawbacks depending on the climate.
C. C. They are more expensive to install than traditional roofs.
D. D. They only help reduce air conditioning costs in hot regions.
✅ Respuesta correcta
B. They have both benefits and drawbacks depending on the climate.
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
