伤寒患者，持续性高热，皮疹，相对缓脉，中毒血症状明显，其临床分型是（）
A.轻型
B.普通型
C.迁延型
D.逍遥型
E.顿挫型
参考答案：B
Poorer families often lack ______ to a car, which they need to drive their children to a more successful school outside their own district.
A．approach
B．access
C．appeal
D．assessment
什么是光纤的非线性？
