Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, a phenomenon where cities are significantly warmer than surrounding rural areas. This happens because concrete, asphalt, and buildings absorb and re-radiate solar heat more than natural landscapes like trees and soil. Additionally, waste heat from vehicles and air conditioners adds to the effect. Now, one surprising solution involves green roofs. A green roof is a layer of vegetation planted on a rooftop. These roofs reduce heat absorption by providing shade and through evapotranspiration—the process where plants release water vapor, which cools the air. Studies show that a green roof can lower rooftop temperatures by up to 40 degrees Fahrenheit during peak summer. However, installation costs are higher than traditional roofs, and maintenance requires regular watering and weeding. Despite these challenges, many cities offer incentives to encourage green roofs, as they also manage stormwater runoff and improve air quality.
❓ Câu hỏi What is the main reason that green roofs help reduce urban heat islands?
A. A) They block sunlight and release water vapor that cools the air.
B. B) They absorb less solar heat than concrete and asphalt.
C. C) They reduce the need for air conditioning in buildings.
D. D) They reflect heat back into the atmosphere.
✅ Đáp án đúng
A) They block sunlight and release water vapor that cools the air.
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
