Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands. Now, as you know, cities tend to be warmer than surrounding rural areas. This is due to several factors, like dark surfaces absorbing heat, lack of vegetation, and waste heat from buildings and vehicles. But there's an interesting solution that's gaining attention: green roofs. Green roofs are covered with vegetation and soil. They help reduce heat in two main ways. First, plants provide shade, which lowers the surface temperature. Second, plants release moisture through transpiration, which cools the air. A study in Chicago found that green roofs can lower rooftop temperatures by up to 40 degrees Fahrenheit. However, there are challenges. Installing a green roof is expensive, and maintenance requires regular watering and weeding. Also, not all buildings can support the extra weight. Despite these issues, many cities are offering incentives to encourage green roof installation, because they also reduce stormwater runoff and improve air quality. So, while the upfront cost is high, the long-term benefits for both the environment and the building owner are significant.
❓ คำถาม What are two main ways green roofs help reduce heat, according to the professor?
A. A. They absorb heat and release moisture.
B. B. They provide shade and release moisture through transpiration.
C. C. They reflect sunlight and reduce waste heat.
D. D. They increase vegetation and lower building weight.
✅ คำตอบที่ถูกต้อง
B. They provide shade and release moisture through transpiration.
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