题目内容：

Besides containing attractive flowers, trees and other plants that beautify the community, eco-friendly rain gardens are healthy for the environment and the people living and working nearby.

A rain garden is not very different from a traditional garden. It is just a far more eco-friendly garden. Usually it is built lower than the ground. Rain gardens make smart use of rain and storm water by temporarily holding water from rain and storms and letting it soak（浸人）slowly into the ground before it runs into streams or enters the public drinking water supply.

Thus, a rain garden keeps the water, allowing it to be used as needed by plants in the rain garden, rather than flowing immediately into nearby streams and going unused. The water will soak slowly into the ground within a day or two. This creates an advantage that the rain garden does not allow mosquitoes to breed. This is a simple, attractive, and eco-friendly “green” way to treat storm water.

What’s more, planting a rain garden helps reduce pollution and improve the environment. Without using expensive machinery and chemicals, rain gardens remove harmful chemicals in the rainwater and cut down on the amount of pollution reaching streams and rivers by up to 30%.

Native plants are recommended for rain gardens because they are more used to the locals climatem, soil, and water conditions. They may attract local wildlife such as native birds. Water your rain garden immediately after planting and once a week, unless you have had at least an inch of rain during the week. Once the native plants establish the necessary root system, it will require little care.

Often, local governments and private businesses develop large rain gardens in their yards and in public parks as a way to improve the environment and solve flooding problems. However, you don’t need to be a professional environmental engineer to create a rain garden. As long as you’re eco-conscious homeowners, you can help the environment by building smaller rain gardens in your yards.

1.Which of the following is the eco-friendly function of rain gardens discussed in Paragraph 4?

    A．They can keep the rain and storm water.

    B．They can help reduce the pollution problem.

    C．They can be healthy for the people around.

    D．They can make the environment more beautiful.

2.One of the main reasons why native plants are recommended is that            .

    A．they cost less and are much easier to get

    B．they may attract local wildlife to come

    C．they require little care from the local gardeners

    D．they are more used to the local growing conditions

3.What do we know about rain gardens?

    A．They need little water after all the plants are planted.

    B．They usually need at least an inch of rainwater a week.

    C．They may attract local birds and change the locals climate.

    D．They may reduce the water pollution problem by 70%.

4.Who are the intended readers of the passage?

    A．Homeowners.  B．Governors.   C．Engineers,   D．Educators.