Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising source of pollution: household detergents. While we often focus on industrial waste, the chemicals from our laundry and dishwashing products can have significant impacts on aquatic ecosystems. Phosphates, for instance, were once common in detergents. When these enter rivers and lakes, they act as fertilizers, causing excessive algae growth. This process, called eutrophication, depletes oxygen in the water, leading to fish kills. In response, many countries banned phosphates in the 1970s, and manufacturers replaced them with other compounds. However, some of these substitutes, like certain surfactants, are not easily biodegradable. They can persist in the environment and disrupt the endocrine systems of fish and other wildlife. So, what can we do? Well, as consumers, we can choose phosphate-free and plant-based detergents. Also, using the correct amount—not overusing—reduces the chemical load on wastewater treatment plants. But ultimately, I believe we need stricter regulations on labeling, so consumers can make informed choices. Does anyone have a question?
❓ 문제 What is the main problem with some detergent substitutes mentioned by the professor?
A. They are more expensive than phosphate-based detergents.
B. They are not easily biodegradable and can harm wildlife.
C. They are less effective at cleaning clothes.
D. They cause immediate algae blooms in rivers.
✅ 정답
They are not easily biodegradable and can harm wildlife.
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