It is nice to know what the weather will be like when we plan a trip. Do you know anything about the history of weather? Don’t look at the sky. Don’t look for old weather reports. Looking at the tree rings is more important. Correct weather reports date back only one century, but some trees can provide an exact record of weather even further back.
It is natural that a tree would grow best in a climate with plenty of sunlight and rainfall. It is also expected that little sunlight or rainfall would reduce the growth of a tree. The change from a favorable to an unfavorable climate can be found out by the reading pattern of rings in a tree trunk. To find out the weather of ten years ago, you can count the rings of a tree trunk from the outside to the inside. If the tenth ring is far from the other rings, then it is certain that plenty of sunny and rainy weather occurred. If the rings are close together, then the climate was bad for the tree.
Studying trees is important not only for the history of weather, but also for the history of man. In an area of New Mexico you can find only sand — no trees or people. However, many centuries ago a large population lived there. They left suddenly. Why?
A scientist studied the pattern of the rings of dead trees that had grown there. He made up his mind that the people had to leave because they had cut down all the trees. Trees were necessary to make fires and buildings. So, after the people destroyed the trees, they had to move.
In this example studying tree rings uncovered an exciting fact about the history of man.
We can find out the weather of five years ago by counting the rings of a tree trunk ____.

A．from the left to the right B．from the right to the left C．from the inside to the outside D．from the outside to the inside

A．bad B．sunny C．favorable D．rainy

A．why the people had to leave B．where the people had to go C．what the people had to eat D．how the people left

A．trees provided an exact record of weather for research B．trees could supply them with fruit and food to live on C．trees could supply them with shades D．trees were materials for fires and buildings

A．trees can’t live in the area without population B．that studying trees is important for the history of man and weather. C．what the real relation is between tree rings and the history of man and weather D．the history of man is important for the history of trees