Listen to part of a lecture in an environmental science class. Professor: Today we’re discussing urban heat islands. As you know, cities are often warmer than surrounding rural areas. This happens because concrete and asphalt absorb and re-emit heat, while vegetation cools the air through evaporation. One common solution is planting more trees. But trees alone aren’t enough. A study in Phoenix, Arizona, found that even with extensive tree planting, nighttime temperatures remained high because the heat stored in buildings and roads during the day is released slowly at night. So, researchers are now looking at reflective roofing materials. These roofs, often white or light-colored, reflect more sunlight and absorb less heat. In simulations, white roofs reduced peak daytime temperatures by up to 2 degrees Celsius. However, their effect is less at night. Another approach is green roofs, which have plants on top. Green roofs provide insulation and also cool the air through evapotranspiration. But they’re more expensive to install and maintain. So, a combination of strategies, including reflective pavements and urban planning, may be necessary.
❓ Question What is the main limitation of planting trees to reduce urban heat islands, according to the professor?
A. Trees do not absorb heat at all.
B. Trees do not help with daytime cooling.
C. Trees alone do not lower nighttime temperatures enough.
D. Trees require too much water in Phoenix.
✅ Correct Answer
Trees alone do not lower nighttime temperatures enough.
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
