We know that trees are useful in our everyday lives. They1us many things, such as wood, oxygen, rubber, medicine and many other things. They can 2 tell us a lot about our climate(气候). The following are the reasons.

If you 3 a tree, you can see that it has many rings(圆圈). Most trees grow one new ring 4year. 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 usually7. When it is wet and warm, the rings are much thicker. If the rings are suddenly very thin or suddenly very thick, this means that the climate changes 8. If we look at the rings on the tree, we can learn about the 9 of a hundred years ago. We can see 10our climate is changing today.