第3题: [单项选择]患者右上第一中切牙扭转近90度，且伴有唇侧倾斜，牙髓正常，牙根长大，牙槽骨轻度吸收，牙龈红肿，探易出血 桩核唇侧应为金属烤瓷冠留出的间隙为 A. 0.5mm B. 1.0mm C. 1.5mm D. 2.0mm E. 1.8mm 参考答案:C 答案解析:前牙金属烤瓷冠牙体预备，唇面应磨除1.5mm，为金属基底冠和瓷面留出足够的空间。桩核的形态就是要恢复预备体的形态，桩核唇侧应为金属烤瓷冠留出的间隙为 1.5mm。
第23题: [简答题]OSPF的域间路由通告行为？问R1能够将AREA 1通告给AREA 0的域间路由在通告回AREA 1吗？为什么？ 参考答案:
NO. This distance vector behavior prevent R1 advertise routes learn from area 1 back to area 1.
According to RFC 2328，there is a rule equivalent of a Distance Vector protocol’s split horizon logic.The rule is described as below： before ABR advertises a summary LSAs（including type 3 and type 4 LSA） to a attached area， if the next hop of the route in the routing table entry belong to the area itself， do not generate a summary-LSA for the route.
