Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'carbon footprint,' which measures the total greenhouse gas emissions caused by an individual, organization, or product. But it's important to realize that carbon footprints can be calculated at different scales. For example, a product's carbon footprint includes emissions from raw material extraction, manufacturing, transportation, and even disposal. However, many people overlook the 'indirect' emissions, such as those from the energy used to produce the materials. Let's consider a simple cotton t-shirt. The direct emissions come from farming machinery and shipping. But indirect emissions include the electricity used in weaving and dyeing. Researchers have found that indirect emissions often outweigh direct ones. So, when we try to reduce our carbon footprint, we need to look beyond just the obvious sources. This brings up a question: how can consumers make informed choices? One way is to look for life-cycle assessments, which analyze all stages of a product's life. Does anyone have thoughts on this?
❓ Question What is the professor's main point about carbon footprints?
A. A. Direct emissions are always greater than indirect emissions.
B. B. Carbon footprints should include both direct and indirect emissions.
C. C. Consumers should ignore life-cycle assessments when buying products.
D. D. The carbon footprint of a t-shirt is too small to matter.
✅ Correct Answer
B. Carbon footprints should include both direct and indirect emissions.
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