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. One major cause is the replacement of natural surfaces with materials like concrete and asphalt, which absorb and retain heat. Another factor is the lack of vegetation, which normally provides shade and cools the air through evapotranspiration. Now, some solutions involve green roofs—planting vegetation on rooftops—which can reduce building energy use by up to 30%. But there's a catch: green roofs are expensive to install and maintain, especially on existing buildings. A more cost-effective approach might be cool roofs, which are painted with reflective materials to bounce sunlight back. Studies show cool roofs are just as effective at lowering surface temperatures, though they don't provide the same biodiversity benefits. So, while green roofs offer ecological advantages, their high upfront costs can be a barrier. This trade-off is something urban planners must weigh.
❓ 문제 According to the professor, what is a key disadvantage of green roofs compared to cool roofs?
A. They are less effective at reducing surface temperatures.
B. They require more maintenance and have higher installation costs.
C. They do not provide any biodiversity benefits.
D. They increase the urban heat island effect.
✅ 정답
They require more maintenance and have higher installation costs.
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