问题
单项选择题
下列哪种结构不参与瞳孔反射传导通路（）
A.视神经
B.动眼神经
C.中脑顶盖前区
D.睫状神经节
E.外侧膝状体
答案
参考答案：E
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下列哪种结构不参与瞳孔反射传导通路（）
A.视神经
B.动眼神经
C.中脑顶盖前区
D.睫状神经节
E.外侧膝状体
参考答案：E
| The most popular organic gem is the pearl. A pearl is the response of a marine mollusk to the presence of an irritating impurity accidentally introduced into its body; a cultured pearl is the result of the intentional insertion of a mother-of-pearl bead into a live mollusk. Whether introduced accidentally or intentionally, the pearl-making process is the same: the mollusk coats the irritant with a substance called nacre. Nacre is composed chiefly of calcium carbonate. Because very few natural pearls are now on the market, most pearls used in free jewelry are cultured. These include "Biwa" pearls and most other freshwater pearls. Cultured pearls are not easily distinguished from natural pearls except by an expert. |
The difference between a pearl and a cultured pearl is the nature of the ______.
A．color
B．introduction of the irritating impurity
C．coating material
D．irritating impurity