Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we’re talking about urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is mainly because concrete and asphalt absorb and re-radiate heat, and there are fewer trees to provide shade and cool through evapotranspiration. But there’s an interesting solution that some cities are adopting: green roofs. A green roof is a roof that is partially or completely covered with vegetation and a growing medium, planted over a waterproof membrane. These roofs can reduce surface temperatures by up to 40 degrees Fahrenheit compared to traditional roofs. They also improve insulation, which lowers energy costs for heating and cooling. Moreover, green roofs absorb rainwater, reducing stormwater runoff and the risk of flooding. Some cities, like Toronto, have even passed bylaws requiring green roofs on new large buildings. However, the initial cost is high, and maintenance can be challenging. Still, many experts argue that the long-term benefits outweigh the upfront expense, especially as climate change intensifies the heat island effect.
❓ 문제 What is the professor's main purpose in the lecture?
A. A. To explain the causes of urban heat islands
B. B. To discuss a potential solution to urban heat islands
C. C. To compare green roofs with traditional roofs
D. D. To describe the history of green roof legislation
✅ 정답
B. To discuss a potential solution 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
