When we think of green buildings, we tend to think of new ones—the kind of high-tech, solar-paneled (装有太阳能板的) masterpieces that ____1____ the covers of architecture magazines. But the U.S. has more than 100 million existing homes, and it would be ____2____ wasteful to tear them all ____3____ and replace them with greener versions. An enormous amount of energy and resources went into the ____4____ of those dwellings. And it would ____5____ 65 years for the reduced carbon emissions from a new energy-effi cient home to make up ____6____ the resources lost by destroying an old one. So in the broadest ____7____, the greenest home is the one that has already been ____8____. But at the same time, nearly half of U.S. carbon emissions come from heating, cooling and ____9____ our homes, offi ces and other buildings. “You can’t deal with climate change ____10____ dealing with existing buildings,” says Richard Moe, the president of the National Trust.

With some ____11____, the oldest homes tend to be the least energy-effi cient. Houses built  before 1939 use about 50% more energy per square foot than ____12____ built after 2000, mainly____13____ the tiny cracks and gaps that expand ____14____ time and let in more outside air. ____15____, there are a tremendous number of relatively simple changes that can green homes, ____16____ historic ones like Lincoln’s Cottage to your own postwar house. And efficiency ____17____ can save more than just the earth; they can help ____18____ house owners from rising power costs. ____19____, a nationwide effort to improve existing buildings could ____20____ hundreds of thousands of green jobs.

1.  A. make  B. become  C. do   D. present

2.  A. fantastically  B. incredibly  C. intriguingly  D. unreliably

3.  A. off   B. away   C. apart  D. down

4.  A. creation  B. construction  C. rebuilding  D. destruction

5.  A. use   B. spend  C. take  D. make

6.  A. at  B. with  C. in   D. for

7.  A. way  B. meaning   C. idea   D. sense

8.  A. built   B. designed   C. destroyed  D. improved

9.  A. electrifying  B. powering  C. equipping   D. generating

10. A. and  B. or  C. without   D. unless

11. A. expectations  B. modifications  C. history   D. exceptions

12. A. much  B. that  C. those  D. as

13. A. with regard to   B. in case   C. due to    D. as to

14. A. with  B. over  C. through     D. during

15. A. Immediately  B. Unexpectedly  C. Fortunately  D. Fundamentally

16. A. from  B. including  C. with  D. for

17. A. changes   B. innovations  C. upgrades   D. boosts

18. A. ensure    B. protect   C. prevent     D. strengthen

19. A. However    B. Nonetheless  C. More or less  D. Moreover

20. A. produce    B. create   C. invent     D. induce