Narrator: Listen to part of a lecture in an environmental science class.
Professor: Today we’re going to talk about a surprising factor in urban climate: the color of rooftops. You might think that trees and parks are the main ways to cool a city, but recent studies suggest that white or reflective roofs can be just as effective, if not more so, in reducing the urban heat island effect. Dark roofs absorb sunlight and convert it into heat, raising the temperature both inside buildings and in the surrounding air. By painting roofs white or using reflective materials, we can bounce sunlight back into space. This not only lowers the need for air conditioning, which saves energy, but also reduces greenhouse gas emissions. Some cities, like Los Angeles, have already mandated cool roofs on new buildings. However, there are challenges. In colder climates, reflective roofs can increase heating costs during winter because they prevent the natural absorption of sunlight. So, while cool roofs are a promising tool, they are not a one-size-fits-all solution. The key is to consider the local climate and the building's design.
❓ Question What is the main topic of the lecture?
A. The benefits of planting trees in urban areas
B. How dark roofs contribute to the urban heat island effect
C. The use of reflective roofs to reduce urban heat and their limitations
D. The history of building regulations in Los Angeles
✅ Correct Answer
The use of reflective roofs to reduce urban heat and their limitations
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
