Nghe TOEFL

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Listen to part of a lecture in an environmental science class. The professor is discussing the concept of urban heat islands. "Now, as we've discussed, urban areas tend to be warmer than surrounding rural areas. This is known as the urban heat island effect. But what causes it? Well, one major factor is the replacement of natural surfaces with materials like concrete and asphalt. These materials absorb and retain heat during the day and release it slowly at night. Another factor is the lack of vegetation. Trees and plants provide shade and release moisture through evapotranspiration, which cools the air. In cities, we've removed much of that vegetation, so less cooling occurs. Additionally, human activities—like driving cars, running air conditioners, and operating industrial facilities—generate waste heat. So, the combination of heat-absorbing surfaces, reduced vegetation, and anthropogenic heat creates a significant temperature difference, sometimes up to several degrees Celsius warmer than the countryside." Now, the professor is going to ask a question.