Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, and specifically how city design can mitigate their effects. One effective strategy is increasing the albedo of rooftops by using reflective materials. When sunlight hits a conventional dark roof, most of the energy is absorbed and then re-radiated as heat. A white or reflective roof, in contrast, reflects a significant portion of that solar radiation back into the atmosphere. This can lower the roof's surface temperature by up to 30 degrees Celsius on a hot day, which in turn reduces the heat transferred into the building below. As a result, air conditioning demand drops, saving energy and reducing greenhouse gas emissions. Another approach is green roofs, where vegetation is planted on the rooftop. These roofs provide insulation, absorb rainwater, and through evapotranspiration, they cool the surrounding air. While green roofs offer multiple benefits, they require more structural support and maintenance. Reflective roofs, however, are cheaper and easier to install, making them a practical first step for many cities.
❓ 質問 What are the two main strategies the professor discusses for mitigating urban heat islands, and what is one advantage of reflective roofs over green roofs?
A. Increasing building height and using darker materials; reflective roofs are more aesthetically pleasing.
B. Using reflective rooftops and green rooftops; reflective roofs are cheaper and easier to install.
C. Planting trees along streets and painting buildings white; green roofs provide better insulation.
D. Installing solar panels and increasing ventilation; reflective roofs require less structural support.
✅ 正解
Using reflective rooftops and green rooftops; reflective roofs are cheaper and easier to install.
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