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问题 单项选择题

洋地黄治疗房颤，减慢心室率的最主要机制是（）

A.直接延长房室结的不应期

B.兴奋迷走神经

C.减慢心房的传导

D.降低心房自律性

E.降低窦房结自律性

答案

参考答案：B

阅读理解

读下面短文，画出家谱图 

    This is my friend John Wilson and his family. This is his grandfather. His name is Fritz. This is his grandmother. Her name is Evelyn. This is his mother. Her name is Anna. This is his father. His name is Earl. Earl’s parents are Fristz and Evelyn. These are his sisters, Christie and Carina.

 1. ______2. ______3. ______4. ______
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单项选择题

若液压A系统压力失效（）

A.对起落架收放没有影响

B.可以由转换活门供压B系统进行起落架的备用收上和放下

C.正常刹车系统和自动刹车系统将不工作

D.在地面，B系统油量正常，可作动备用转弯电门进行备用前轮转弯
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