53.The underlined word “it” refers to ______________.　

A. the intention　 B. the collection　C. one member　　 D. each flower family　

52. It can be inferred from the passage that the goal of Leopold and Rudolph was to ______________.　

A. create a botanical garden where only exotic flowers grew　

B. do a thorough study of plant structure　

C. make a copy of one member of each United States flower family　

D. show that glass are more realistic than wax flowers　

51. Which of the following is the best title for the passage?　

A. An Extensive Collection of Glass Flowers 　

B. The Lives of Leopold and Rudolph　

C. Flowers Native to the United States　

D. Material Used for Artificial Flowers　

50.C。主旨大意题。文章最后一自然段中点明了主题：A lot of them know that conservation is necessary.

C(words:190&203)

Artificial(假的) flowers are used for scientific as well as for decorative purposes. They are made from a variety of materials, such as wax and glass, so skillfully that they can scarcely be distinguished from natural flowers. In making such models, painstaking and artistry are called for, as well as thorough knowledge of plant structure. The collection of glass flowers in the Botanical Museum of Harvard University is the most famous in North America and is widely known throughout the scientific world. In all, there are several thousand models in colored glass, the work of two artist-naturalists, Leopold Blaschka and his son Rudolph.

The intention was to have the collection represent at least one member of each flower family native to the United States. Although it was never completed. It contains more than seven hundred species representing 164 families of flowering plants, a group of fruits showing the effect of fungus diseases, and thousands of flower parts and magnified details. Every detail of these is accurately reproduced in color and structure. The models are kept in locked cases as they are too valuable and fragile for classroom use.　

49.C。推理判断题。根据文章第二自然段可推出此答案。

48.B。推理判断题。根据文章最后一自然段倒数第三句Young people may hear about conservation through a record called “No, One's Going to Change our World. ”可知。

47.C。细节理解题。根据第一自然段最后两句We can't live without these things. If we continue like this, we shall destroy ourselves.可知。

46.C。推理判断题。根据第一自然段内容可知。

50. What’s the main idea of the passage?　

A. 1970 was “World Conservation Year”.　

B. The United Nations wanted everybody to know that the world is in danger.　

C. Conservation is necessary.　

D. It is the young people who are helping to save our world .

[答案与解析]　 46-50 CCBCC

49. What is the most important thing for us to do to save our world?

A. We should clean the banks of our rivers.　

B. We should know what will happen in the future.　

C. We should know what we should do and do it now.　

D. We should plant more trees and flowers.