Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'urban heat islands,' where cities are significantly warmer than surrounding rural areas. This happens mainly because concrete and asphalt absorb and re-radiate solar heat, whereas vegetation and soil have cooling effects. But there are solutions. One emerging approach is 'cool roofs,' which are designed to reflect more sunlight than traditional dark roofs. They can be coated with special reflective paints or made from reflective tiles. Studies show that cool roofs can reduce a building's cooling costs by up to 15% in hot climates. However, there's a catch. In colder regions, cool roofs might increase heating costs during winter because they reflect away the sun's warmth when it's actually beneficial. Therefore, scientists suggest a 'smart roof' that can switch between reflective and absorptive modes depending on the season. This adaptive technology is still under development, but it holds promise for optimizing energy efficiency across diverse climates.
❓ Câu hỏi What is the main challenge mentioned regarding cool roofs?
A. They are too expensive for most homeowners.
B. They may increase heating costs in cold regions.
C. They do not reflect enough sunlight in summer.
D. They are only effective in tropical areas.
✅ Đáp án đúng
They may increase heating costs in cold regions.
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