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, when it rains heavily in a city, the water has nowhere to go because of all the concrete and asphalt. This causes flash floods. Traditional solutions, like building bigger drains, are expensive and often insufficient. However, green roofs—roofs covered with vegetation and soil—can absorb a significant amount of rainwater. In fact, studies have shown that a green roof can retain up to 70% of rainfall during a moderate storm. The plants and soil act like a sponge, slowing down the release of water into the drainage system. This not only reduces the peak flow of water but also filters pollutants. Additionally, green roofs provide insulation, which lowers energy costs for the building. So, while the initial installation might be pricier than a standard roof, over time, the benefits outweigh the costs. Now, some critics argue that green roofs are too heavy and require extensive maintenance. But engineers have developed lightweight materials and drought-resistant plants, making green roofs viable even in arid climates. So, we're seeing more cities adopt this nature-based solution.
❓ Question What is the main benefit of green roofs discussed in the lecture?
A. They reduce energy costs by providing insulation.
B. They help manage urban flooding by absorbing rainwater.
C. They are cheaper to install than traditional roofs.
D. They require no maintenance in dry climates.
✅ Correct Answer
They help manage urban flooding by absorbing 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
