Listen again to part of the lecture．Then answer the question. What does the professor imply about the behavior. of the snakes？
A. The snakes' behavior. is a warning signal to other animals.
B. Temperature plays an important role in the snakes' behavior.
C. Scientists can observe the snakes' behavior. in their winter dens.
D. The snakes are able to learn a variety of behavioral responses.
查看答案
The word them in the passage refers to
A. less-developed nations.
B. individuals.
C. bonds.
D. primary groups.
Why does the professor say this:
A. To praise the area's beautiful winter scenery
B. To persuade students to build their own homes
C. To describe the most common one of limestone
D. To explain why so many snakes live in the region
How do the garter snakes deal with seasonal variations in temperature？
A. They grow an extra layer of skin in winter and shed it in summer.
B. They survive by migrating toward the south every winter.
C. They move into the limestone pits to escape winter temperatures.
D. They vary their food intake to maintain a constant body temperature.
The word secretes in the passage is closest in meaning to
A. produces.
B. allows.
C. contains.
D. transforms.
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