单项选择题

Directions: There are 10 blanks in the following passage. For each numbered blank, there are 4 choices marked A, B, C and D. Choose the best one and mark your answer on the ANSWER SHEET with a single line through the center.
Artificial flowers are used for scientific as well as for decorative purposes. They are made from 1 of materials, such as wax and glass, so skillfully that they can scarcely be 2 from natural flowers. In making such models, painstaking skill and artistry are called for, 3 thorough knowledge of plant structure. The 4 of glass flowers in the Botanical Museum of Harvard University is the most famous in North America and is widely known 5 the scientific world. 6 , there are several thousand models in colored glass, the work of two artist-naturalists, Leopold Blalschka and his son Rudolph.
The intention was to have the collection 7 at least one member of each flower family native to the United States. 8 it was never completed, it contains more than seven hundred species representing 164 families of flowering plants. 9 detail of these is accurately reproduced in color and structure. The models are 10 in locked cases as they are too valuable and fragile for classroom use.

A. a variety
B. some
C. a sort
D. several