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问题 单项选择题

数据模型用来表示实体间的联系，但不同的数据库管理系统支持不同的数据模型。在常用的数据模型中，不包括( )。

A．网状模型

B．链状模型

C．层次模型

D．关系模型

答案

参考答案：B

单项选择题

女性，28岁，停经45天， * * 不规则出血1周；尿妊娠试验阳性；结合超声图像（彩图36），最可能的诊断是（）。

A.附件炎性包块

B.异位妊娠

C.卵巢肿瘤

D.子宫肌瘤

E.卵巢畸胎瘤
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单项选择题

A local-area network (LAN) is a communications network that (125) a variety of devices and provides a (126) for information exchange among those devices. The scope of the LAN is small typically a single building or a cluster (丛) of buildings. The LAN is usually owned by the same organization that owns the (127) devices. The internal data rate of LAN is at least several Mb/s.
The basic of LAN communication is broadcasting. At each station, there is a transmitter/receiver that communicates over a (128) shared, By other stations. A transmission from any one station is (129) to and received by all other stations.

A．broadcast

B．cable

C．control

D．interconnects

E．internet

F．meander

G．means

H．medium

I．modem

J．output switch relay
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