完形填空。
We know that trees are useful in our everyday life. They    1   us many things, such as wood, rubber,
medicine and many other things. They can    2    tell us a lot about our climate (气候). If you    3    a tree,
you can see that it has many rings (年轮). Most trees get a new ring    4   year. Because of this reason, we
know    5    a tree is. A tree over a hundred years old means that it has more than a hundred    6    . When
the climate is dry or very cold, the trees do not grow very much and their rings are usually    7    . When it is
wet and warm, the rings are much thicker. If the rings are suddenly (突然地) very thin or very thick, this
means that the    8    changed suddenly. If we look at the rings on this tree, we can learn    9    the climate
for a hundred years. And we can see   10   our climate is changing today.
(     )1. A. tell
(     )2. A. not
(     )3. A. cut down
(     )4. A. many
(     )5. A. how big
(     )6. A. trees
(     )7. A. big
(     )8. A. climate
(     )9. A. about
(     )10. A. when

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