Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising solution to urban flooding: green roofs. Now, traditional roofs are impermeable—water runs off quickly, overwhelming storm drains. Green roofs, however, are covered with vegetation and soil. They absorb rainwater like a sponge, releasing it slowly. A study in Portland, Oregon, found that a green roof can retain up to 70% of rainfall during a typical storm. But the benefits go beyond flood control. Green roofs also reduce the urban heat island effect, since plants cool the air through evapotranspiration. And they extend the lifespan of the roof membrane because they shield it from UV radiation and temperature swings. Of course, there are challenges: initial costs are higher, and the roof must be structurally reinforced to support the extra weight. But many cities now offer tax incentives to offset these expenses. So, while green roofs are not a silver bullet for all urban flooding, they are a key part of a multi-pronged approach. Any questions?
❓ Pregunta According to the professor, what is one way green roofs help with urban flooding?
A. A. They completely eliminate the need for storm drains.
B. B. They slow down the release of rainwater.
C. C. They increase the weight of the roof, making it stronger.
D. D. They reflect sunlight to cool the surrounding air.
✅ Respuesta correcta
B. They slow down the release of rainwater.
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