宋高宗在收回边境兵权的过程中达到了北宋中央对于地方兵权的控制程度

一个三角形的底和高是两个相邻的自然数，且底小于高，它的面积是21平方厘米．底和高各是多少分米．

去年4月，我国出现H7N9禽流感疫情，请依据图中疫病防控信息回答问题

（1）截止到5月底，我国防控禽流感工作由应急状态转为常态化．引起本次禽流感的病原体是______，H7N9禽流感是一种传染病，是因为这种病主要具有______等特点．

（2）图1中属于预防传染病的哪一措施？______；收治禽流感病人后，医院应采取的措施是______；属于切断传播途径的措施有（用图中序号填空）______．

（3）图中5所示，禽流感疫苗接种到人体中以后，会使人体产生相应的______，从而提高对该流感的抵抗力，这种措施属于传染病预防措施中的______，这样获得的免疫属于______，这种免疫是由______完成的．

（4）小敏接种过乙肝疫苗，他认为自己体内有抗体，不会患上这种传染病．他的想法对吗？______．为什么？______．

某药的消除符合一级动力学，其t_1/2为4h，在定时定量给药后，需经多少小时才能达到稳态血药浓度（）

A.约10h

B.约20h

C.约30h

D.约40h

E.约50h

For each blank, choose the best answer from the four choices and write down on the answer sheet.
(66) is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.
(67) is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.
(68) functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.
(69) is the popular LAN developed under the direction of the IEEE 802.5.
(70) is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.

A．X.25

B．ATM

C．FDDI

D．SMDS

生物礁是一种（）建造，造物礁主要是珊瑚藻。