阅读下面材料，然后从各题所给的四个选项中选出一个最佳答案．

     Fresh green grass． Hundreds of colorful wild flowers． Water running into little pools． Birds making their homes in boxes． The 9， 500﹣square﹣metre Augustenborg Botanical Garden may look just like any other well﹣organized park but there's a difference． It lies on the roofs（屋顶） of industria land office buildings in the city of Malmo in Sweden．

     Green roofs are not a new invention． And now they are getting popular again． The common roofs of a modern city have endless black surfaces with no life or water． Perhaps that's why a garden on a roof becomes such a perfect choice for more and more people．

     Green roofs are not just pretty． They also help to moderate the city temperature． The high temperatures on common roofs in the summer can make top floor flats uncomfortably hot． What is more， they play a part in making the cities hotter than the countryside around them， causing the "urban heat﹣island effect"． On a green roof， however， with its plants and water， temperatures change only a little， as they do in a park． This can greatly cut the costs of heating and cooling in the building below．

     Also， a green roof takes in rain water， and protects the city drainage（排水） system．_____ And small animals and birds can make their homes on it． Thanks to this， the city may become part of nature， rather than something completely separate from it．

    While the cost of building such a roof can still be higher， it can be cheaper in the long term as a result of energy savings． And wouldn't it be wonderful to be able to walk out into a garden high above the city's noise and traffic， whether you're at school or in an office or just at home in a ten﹣floor block．

（1）With the example of Augustenborg Botanical Garden， the writer wants to explain　　．

A． how wildlife is protected

B． what a green roof is like

C． how to organize a good park

D． what to do with a spare roof

（2）The underlined word " moderate" in Paragraph 3 is the closest in meaning to "　　"．

A． raise

B． check

C． record

D． control

（3）Which of the following is the best sentence to fill in the blank in Paragraph 4？　　

A． A green roof is alive．

B． A green roof stops pollution．

C． A common roof is noisy．

D． A common roof increases the cost．

（4）The purpose of the passage is to　　．

A． discover the problems with green roofs

B． introduce the change of green roofs

C． show the amazing beauty of green roofs

D． describe the advantages of green roofs