Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising solution to reducing urban heat—green roofs. Now, you might think that planting vegetation on rooftops is just about aesthetics, but research shows it has significant cooling effects. A study in Toronto compared two similar buildings: one with a traditional dark roof, and one with a green roof covered in sedum plants. Over a hot summer day, the surface temperature of the green roof was up to 30 degrees Celsius cooler than the conventional roof. But the benefits go beyond the building itself. The plants absorb sunlight for photosynthesis, releasing moisture through transpiration, which cools the surrounding air. This can lower the ambient temperature by a few degrees, potentially reducing the urban heat island effect. However, there are challenges, such as upfront costs and the need for waterproofing and structural support. Yet, over time, green roofs can reduce energy costs for heating and cooling, and they also manage stormwater runoff. So, while the initial investment is higher, the long-term environmental and economic gains often outweigh the drawbacks.
❓ Question What is the main benefit of green roofs discussed by the professor?
A. A. They improve the aesthetic appearance of buildings.
B. B. They significantly reduce surface and ambient temperatures.
C. C. They require less maintenance than traditional roofs.
D. D. They eliminate the need for waterproofing in buildings.
✅ Correct Answer
B. They significantly reduce surface and ambient temperatures.
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