Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising factor that affects urban temperatures: the color of rooftops. Most of you know about the urban heat island effect, where cities are warmer than surrounding rural areas due to concrete and asphalt absorbing heat. But did you know that simply painting rooftops white can significantly reduce this effect? White roofs reflect sunlight, whereas dark roofs absorb it. Studies in cities like New York and Los Angeles have shown that white roofs can lower rooftop temperatures by up to 30 degrees Celsius on hot days. This not only reduces the need for air conditioning inside buildings, but it also helps mitigate the overall city temperature. However, there are some drawbacks. In colder climates, white roofs might increase heating costs during winter because they reflect sunlight that could otherwise warm buildings. So, the decision to use white roofs isn't always straightforward. It depends on the local climate and energy needs.
❓ 質問 What is the main point the professor makes about white roofs?
A. They are universally beneficial for reducing energy costs.
B. They are most effective in warm climates but may be less practical in cold ones.
C. They cause the urban heat island effect to worsen.
D. They are too expensive to implement on a large scale.
✅ 正解
They are most effective in warm climates but may be less practical in cold ones.
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