Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'urban heat islands.' This phenomenon occurs when cities are significantly warmer than surrounding rural areas. The main cause is the replacement of natural land cover with materials like asphalt and concrete, which absorb and retain heat. Additionally, waste heat from vehicles and air conditioning systems contributes. One surprising factor is the lack of vegetation. Trees and green spaces cool the air through evapotranspiration, but in dense cities, these are often scarce. To combat this, some cities have implemented 'green roof' programs, where roofs are covered with plants. A study in Chicago showed that green roofs can reduce surface temperatures by up to 40 degrees Fahrenheit on hot days. However, the initial cost is high, and maintenance requires water and care. Still, the long-term energy savings for buildings can offset these expenses. Now, let's consider the social implications...
❓ Câu hỏi What is the main cause of urban heat islands, according to the professor?
A. A. The lack of public transportation
B. B. The replacement of natural surfaces with heat-absorbing materials
C. C. The excessive use of air conditioning in buildings
D. D. The high density of tall buildings blocking wind
✅ Đáp án đúng
B. The replacement of natural surfaces with heat-absorbing materials
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
