1. (2019七下·广州期中) 阅读理解

    American researchers have successfully developed a way to clean waste water without chemicals. The technique uses green plants. The tests were carried out at waste treatment centre. The scientists put plants in narrow containers inside a glass building. One end of each container was a little higher than the other end. Waste water was directed down the containers through the plants' thick roots as we expected. The roots absorbed the waste in the water and used it for food. At the same time the plants produced natural gas. The gas could be collected and sold as fuel(燃料).

    Four places in Florida are already using green plants to clean their waste water.

1. （1） The best title for this passage is "      ".

   A . The success of American scientists B . A new way to treat waste water C . Waste water and green plants D . Advanced technology in America
3. （2） The technique to clean waste water is based on the fact that     .

   A . green plants can be put in narrow containers B . most green plants have thick roots C . water can be directed down through the plants' thick roots D . the waste in water is excellent food for plants
5. （3） The technique is called a new way because       .

   A . it is cheaper than any other one B . it can be carried out in a glass building C . it makes the waste water clean but uses no chemicals D . it needs only narrow containers and green plants
7. （4） The new technique       .

   A . has come to be widely used in America B . is still being tested since its first use C . proved to be more valuable than expected D . has now come into use in some places of America