题目内容：

The chaparral ecosystem is a plant and animal community that is relatively rare. It is characterized by shrub­land and a specific weather pattern. Winters in this ecosystem are mild and wet, and summers tend to be hot and dry. The state of California in the United States has one of the world's largest chaparral ecosystems. They can also be found in parts of northern Mexico, Australia, Chile, and South Africa.

Wildfires occur frequently in this ecosystem. Lots of very flammable plant growth builds up in between fire seasons. Only about 15­39 inches of rainfall each year. Shrub plants of the chaparral are most likely to catch fire in the late summer or early fall. That's because the summers are extra dry. The thought of fire is frightening to people with homes or businesses. However, it is far more dangerous not to have wildfires. When there are no fires, the shrubs take over. Small fires once in a while are beneficial. They keep the plant growth under control. They also act in some other surprising ways. There are some plant species in chaparral ecosystems that cannot reproduce unless there has been a fire. The heat, smoke and changes in the soil that follow a burn actually release seeds from some plants.

What causes the frequent fires in this region? Sometimes lightning strikes will catch plants on fire. However, this accounts for only a small portion of the fires. Humans are the cause of many wildfires. A match, cigarette or campfire left carelessly unattended can cause a fire. Hot, dry winds, like the Santa Ana winds in California, make the fire go wild.If it has been a long time since the last fire, plants will fuel the fire. It is often very difficult for firefighters to put out these fires.

People who live in and near chaparral ecosystems have to clear plants from around their homes. This helps to prevent the home from being damaged in a fire. Wildfires are a natural and important part of a healthy chaparral ecosystem.

1.According to the first two paragraphs, the chaparral ecosystem________.

A. can be found throughout northern Mexico

B. has a lot of rainfall in winters

C. can easily catch fire in summers

D. has few plants and animals

2.What can we infer from the passage?

A. Broad­leaves plants are less likely to catch fire here.

B. Shrub plants will damage the eco­balance without wildfires.

C. Plants can't reproduce without wildfires.

D. Humans here are threatened to leave by frequent fires.

3.What can people do to prevent accidental fires?

A. They should be careful with matches, cigarettes and campfires.

B. They should prevent lighting striking.

C. They should train well­equipped firefighters.

D. They should clear flammable plants.

4.What is the main idea of the passage?

A. Wildfires are an important part of the chaparral ecosystem.

B. People can take steps to remain safe in the chaparral ecosystem.

C. Wildfires occur frequently in the chaparral ecosystem.

D. The chaparral ecosystem is relatively rare in the global area.