Narrator: Listen to part of a lecture in an environmental science class. Professor: Today, let's talk about urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is because concrete and asphalt absorb and re-radiate heat more than vegetation does. Additionally, waste heat from vehicles and air conditioners adds to the effect. But here's an interesting solution: green roofs. By covering rooftops with plants and soil, buildings can reduce heat absorption. Studies show that a green roof can lower the surface temperature of a roof by up to 40 degrees Celsius compared to a traditional black roof. This not only cools the building, reducing energy costs, but also helps mitigate the overall urban heat island effect. However, green roofs require regular maintenance, such as watering and weeding, which can be costly. Some cities offer tax incentives to offset these costs. So, while the initial investment is high, the long-term benefits—both environmental and economic—are significant.
❓ Pregunta What is the main purpose of the lecture?
A. To explain why cities are warmer than rural areas
B. To discuss the disadvantages of green roofs
C. To introduce green roofs as a solution to urban heat islands
D. To compare different types of roofing materials
✅ Respuesta correcta
To introduce green roofs as a 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
