1.     We know that trees are useful in our everyday life. They give us 1 things, such as wood, oxygen, rubber（橡胶）, medicines 2 many other things. They can also tell us a lot about our climate. The following are the reasons. If you cut 3 a tree, you can see that it has many rings. Most trees grow one new ring 4 year. Because of this, we know how old a tree is. A tree over a hundred 5 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 7 usually thin. When it is wet and warm, the rings
8 thicker. If the rings are suddenly very thin or suddenly very thick, it means that the 9 changed suddenly. If we look at the rings on the tree, we can learn about the climate in the past years. We can see
10 changing today.