Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising factor in climate change: the role of forests. Most of you know that trees absorb carbon dioxide, but did you know that they also release volatile organic compounds, or VOCs? These compounds, like isoprene, can react with nitrogen oxides in the atmosphere to form ozone, a greenhouse gas. However, the story isn't simple. In polluted areas, with high nitrogen oxide levels from traffic or industry, VOCs can increase ozone, worsening air quality. But in clean, remote areas, VOCs actually help remove pollutants by forming aerosols that scatter sunlight and cool the Earth. So forests have a dual effect: they store carbon, but their emissions can either warm or cool the planet depending on local conditions. This complexity makes it tricky for policymakers to rely solely on planting trees as a climate solution. We need to consider where and how we reforest.
❓ Pregunta What is the main point the professor makes about forests and climate change?
A. Forests always help reduce global warming by absorbing carbon dioxide.
B. Forests have both cooling and warming effects that depend on local pollution levels.
C. The main problem with forests is that they release too many nitrogen oxides.
D. Planting more trees is the most effective way to combat climate change.
✅ Respuesta correcta
Forests have both cooling and warming effects that depend on local pollution levels.
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
