Listen to part of a lecture in an environmental science class. Professor: Today we're going to discuss a surprising factor in climate change: the role of forests. While we often think of trees as carbon sinks, they also release volatile organic compounds, or VOCs. These compounds can react with nitrogen oxides in the atmosphere to form aerosols. Aerosols, in turn, have a cooling effect because they reflect sunlight back into space. This is a complex feedback loop. For example, in the Amazon, trees release immense amounts of isoprene, a type of VOC. During the wet season, when the trees are most active, the release peaks, and cloud formation increases. However, human activities, such as deforestation and air pollution, disrupt this balance. Deforestation reduces VOC emissions, while increased nitrogen oxides from pollution can alter aerosol formation, potentially leading to warming. So, the interaction between forests and the atmosphere is more nuanced than we once thought.
❓ คำถาม What is the main point the professor makes about forests?
A. A) Forests are primarily carbon sinks that cool the climate.
B. B) Forests release chemicals that can have both cooling and warming effects.
C. C) Deforestation increases aerosol formation and leads to cooling.
D. D) Nitrogen oxides from forests are the main cause of climate change.
✅ คำตอบที่ถูกต้อง
B) Forests release chemicals that can have both cooling and warming effects.
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