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-emit heat from the sun more than natural landscapes do. Additionally, waste heat from vehicles and air conditioners adds to the effect. One major consequence is increased energy consumption for cooling, which leads to higher greenhouse gas emissions. But there are solutions. Green roofs, which are covered with vegetation, can reduce rooftop temperatures by up to 40 degrees Celsius. They also improve insulation, reducing heating costs in winter. Another approach is increasing urban tree cover, which provides shade and cools the air through evapotranspiration. However, these measures require upfront investment and maintenance. Some cities, like Toronto, have implemented bylaws requiring green roofs on new buildings. So, while the problem is serious, there are practical steps we can take to mitigate it.
❓ 문제 What is the main topic of the lecture?
A. A. The benefits of green roofs for winter heating
B. B. The causes and potential solutions for urban heat islands
C. C. The difference in temperature between cities and rural areas
D. D. The role of trees in reducing air pollution
✅ 정답
B. The causes and potential solutions for 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