Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands. This phenomenon occurs when cities are significantly warmer than surrounding rural areas. The main cause is the replacement of natural surfaces with concrete and asphalt, which absorb and retain heat. Additionally, buildings and vehicles generate waste heat. One surprising solution is green roofs—rooftops covered with vegetation. A study in Chicago found that green roofs can reduce rooftop temperatures by up to 40 degrees Fahrenheit in summer. They also reduce stormwater runoff by absorbing rainwater. However, the initial cost of installing a green roof is higher than a traditional roof, but over time, energy savings and extended roof lifespan can offset that expense. Some cities now offer tax incentives to encourage green roof installation. Professor: So, what's the key takeaway? Green roofs are a practical, long-term investment for urban sustainability.
❓ Câu hỏi What is the main purpose of the lecture?
A. To explain why urban heat islands occur and discuss a solution
B. To compare the costs of different types of roofing materials
C. To describe the history of green roof technology in Chicago
D. To argue that urban heat islands are unavoidable
✅ Đáp án đúng
To explain why urban heat islands occur and discuss a solution
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