Narrator: Listen to part of a lecture in an environmental science class.
Professor: Today, let's discuss a surprising factor in climate change: the role of forests. You might think planting more trees always helps, but it's more complex. Trees absorb carbon dioxide, yes, but they also release volatile organic compounds, or VOCs. These compounds can react with nitrogen oxides in the atmosphere to form ozone and aerosols, which can actually have a warming effect. In some regions, especially where pollution is high, the net effect of forests on temperature might be neutral or even positive. However, this doesn't mean deforestation is good. Mature forests store massive amounts of carbon in their soil and biomass, and when they're cut down, that carbon is released. So, we need to consider the full lifecycle of a forest. For example, a young, fast-growing forest absorbs CO2 quickly but may emit more VOCs, while an old-growth forest stores more carbon but grows slowly. The key is to protect existing forests and manage new ones wisely, taking into account local conditions.
❓ Câu hỏi What is the main point the professor makes about forests and climate change?
A. Planting trees is always beneficial to the climate.
B. Forests can both absorb carbon dioxide and release compounds that may warm the atmosphere.
C. Deforestation has little effect on global temperatures.
D. Old-growth forests are worse for the climate than young forests.
✅ Đáp án đúng
Forests can both absorb carbon dioxide and release compounds that may warm the atmosphere.
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
