Narrator: Listen to part of a lecture in an environmental science class. Professor: Today, let's talk about urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is mainly because concrete and asphalt absorb and re-radiate heat more than vegetation does. But there are solutions. One effective strategy is planting more trees, which provide shade and release moisture through transpiration. Another is using reflective materials on rooftops, often called cool roofs. These materials reflect sunlight instead of absorbing it, reducing the need for air conditioning. Interestingly, a study in Los Angeles found that a combination of cool roofs and street trees could lower city temperatures by up to 3 degrees Celsius. However, there is a trade-off: cool roofs reflect heat upward, which might actually increase temperatures for pedestrians at street level. So, urban planners must weigh the benefits and drawbacks carefully. Now, let's consider how these strategies might be adapted to different climates.
❓ Question What is the professor's main point about cool roofs?
A. They are always more effective than planting trees.
B. They have potential drawbacks despite their benefits.
C. They are not recommended for hot climates.
D. They work best when used alone in urban areas.
✅ Correct Answer
They have potential drawbacks despite their benefits.
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
