Narrator: Listen to a conversation between a student and her biology professor.
Student: Professor, I wanted to ask about the field trip to the wetland next week. I’m worried about the water quality tests we’re supposed to do.
Professor: Oh, don’t worry. We’ll use simple kits—just measure pH and turbidity. The main goal is to observe how seasonal changes affect macroinvertebrate populations.
Student: Right, but I read that macroinvertebrates are sensitive to pollution. So if we find fewer species, does that mean the water is bad?
Professor: Exactly. Some species, like stoneflies, only live in clean water. If we find them, it’s a good sign. But if we only see worms or leeches, that indicates higher pollution levels.
Student: Got it. And we’ll compare our data with last spring’s records?
Professor: Yes, that’s the key. You’ll see if the wetland has improved or declined. Remember to bring waterproof boots—the ground will be muddy.
Student: Thanks, Professor. I’ll be prepared.
❓ Question What is the main purpose of the field trip mentioned in the conversation?
A. To practice using water testing equipment in a real environment
B. To compare current macroinvertebrate populations with past data to assess wetland health
C. To identify all species of insects living in the wetland
D. To measure the effect of seasonal changes on water temperature
✅ Correct Answer
To compare current macroinvertebrate populations with past data to assess wetland 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