Listen to part of a lecture in an environmental science class.
Today we're going to talk about a surprising source of pollution: household dust. You might think dust is just dirt, but it's actually a complex mixture of particles, including dead skin cells, pet dander, and tiny fibers from clothing and furniture. However, what concerns researchers is the presence of chemicals called flame retardants. These chemicals are added to many household products, like sofas and electronics, to slow down burning. Over time, they break down and become part of the dust in our homes. Studies have shown that people, especially young children who spend time on the floor, can ingest or inhale these particles. The health effects are still being studied, but some flame retardants have been linked to hormone disruption. So, what can you do? Simple steps like regular vacuuming with a HEPA filter and washing hands before eating can help reduce exposure. But the broader solution involves manufacturers finding safer alternatives.
❓ Câu hỏi What is the main point the professor makes about household dust?
A. It is primarily made up of dead skin cells and dirt.
B. It contains harmful chemicals that can affect health.
C. It can be completely eliminated with proper cleaning.
D. It is more dangerous to adults than to children.
✅ Đáp án đúng
It contains harmful chemicals that can affect health.
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