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问题 选择题
已知椭圆
x2
a2
+
y2
b2
=1 (a＞b＞0)的右焦点为F，ℓ为右准线，过F作椭圆的弦AB，以AB为直径的圆与ℓ的关系（　　）
A．相交B．相切C．相离D．不确定
答案

过焦点的弦为AB的中点是M且到准线的距离是d，设A到右准线的距离d1=|PF|，B到准线的距离d2=|QF|．

结合中位线的定义与椭圆的定义可得：所做圆的半径r=

1
2
AB，

∵

AF
d1
=
BF
d2
=e，0＜e＜1

∴

1
2
（d1+d2）=
1
2
•
AF+BF
e
=
AF+BF
2e
=
AB
2
•
1
e
＞
AB
2
=r

由直线与圆的位置关系可知，直线与圆相离

故选C

单项选择题

按广东农村信用社支付结算业务中支票业务的相关规定，以下对人民银行签发空头支票进行行政处理的要求描述正确的是（）

A.人民银行收到开户银行的相关资料后，需在3个工作日内进行核实，并作出是否进行行政处罚的决定

B.人民银行收到开户银行的相关资料后，需在5个工作日内进行核实，并作出是否进行行政处罚的决定

C.人民银行收到开户银行的相关资料后，需在10个工作日内进行核实，并作出是否进行行政处罚的决定

D.人民银行收到开户银行的相关资料后，需在3个工作日内进行核实，在5个工作日内作出是否进行行政处罚的决定
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单项选择题

One of the most widely used routing protocols in IP networks is the Routing Information Protocol (RIP). RIP is the canonical example of a routing protocol built on the (71) algorithm. Routingprotocols in internetworks differ slightly from the idealized graph model. In an internetwork, the goal ofthe routers to forward (72) to various networks.
Routers running RIP send their advertisement abOLit cost every (73) seconds. A router also sends an up date message whenever an update from another router causes it to change its routing table.
Routing protocols use different techniques for assigning (74) to individual networks. Further, each routing protocol forms a metric aggregation in a different way. RIP takes the simplestapproach, with all link costs being equal (75) . Thus it always tries to find the minimum hop route. Valid distances are 1 through 15. This also limits RIP to running on fairly small networks.

A．1
B．15
C．16
D．length of the link
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