受各种因素的影响，今年大蒜价格始终居高不下，影响了人们对大蒜的需求．大蒜具有一定的抗病功能和食疗价值，大蒜新素（C6H10S3）是其有效成分之一．下列关于大蒜新素的说法正确的是（ ）
A．C、H、S元素质量比为6：10：3
B．属于混合物
C．大蒜新素中含有三个硫原子
D．相对分子质量为178
A、大蒜新素（C6H10S3）中C，H，S元素质量比为：（12×6）：（1×10）：（32×3）=36：5：48，故A错误；
B、混合物是由两种或两种以上物质组成的物质，大蒜新素是一种物质，故不属于混合物，故B错误；
C、大蒜新素是由分子构成的，不是由原子构成的，故C说法错误；
D、相对分子质量是指构成分子的各原子的相对原子质量之和，故大蒜新素（C6H10S3）的相对分子质量为：12×6+1×10+32×3═178，故D正确；
故选D
| Artificial flowers are used for scientific as Well as for decorative purposes. They are made from (51) of materials, such as wax and glass, so skillfully that they can scarcely be (52) from natural flowers. In making such models, painstaking skill and artistry are called for, (53) thorough knowledge of plant structure. The (54) of glass flowers in the Botanical Museum of Harvard University is the most famous in North America and is widely known (55) the scientific world. (56) , 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 (57) at least one member of each flower family native to the United States. (58) it was never completed, it contains more than seven hundred species representing 164 families of flowering plants. (59) detail of these is accurately reproduced in color and structure. The models are (60) n locked cases as they are too valuable and fragile for classroom use. |
A．concentration
B．gathering
C．collection
D．assembly