What is the text about？
A. What is a tree ring.
B. What can a tree ring do.
C. How to study a tree ring.
【B5】
A. hundred
B. hundreds
C. thousand
【B2】
A. was
B. is
C. had been
What is not true？
A. People can know the weather hundreds of years ago by studying the tree ring.
B. People can study the history of man from tree rings.
C. People can know what animals had once lived from tree rings.
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