Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'urban heat islands.' As cities grow, they replace natural surfaces like soil and vegetation with asphalt, concrete, and buildings. These materials absorb and retain heat from the sun much more than natural landscapes do. Additionally, human activities—such as driving cars, running air conditioners, and industrial processes—generate waste heat. All of this causes urban areas to be significantly warmer than surrounding rural areas. For example, on a clear summer night, the temperature difference can be as much as 10 degrees Celsius. One surprising effect is that this heat can actually increase air pollution, because warmer temperatures accelerate the chemical reactions that produce ground-level ozone. To mitigate this, some cities have started planting green roofs and more trees, which provide shade and cool the air through evapotranspiration. However, these solutions require careful planning and maintenance. So, while urban heat islands are a challenge, they are not insurmountable.
❓ คำถาม What is the main point the professor makes about urban heat islands?
A. They are caused solely by the lack of vegetation in cities.
B. They result from both surface materials and human-generated heat.
C. They have no effect on air quality in urban areas.
D. They are easily solved by planting trees without any maintenance.
✅ คำตอบที่ถูกต้อง
They result from both surface materials and human-generated heat.
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
