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问题 单项选择题

一重物放在地面上，如图所示，P是重物的重力，FN是重物对地面的压力，是地面对重物的约束力，作用力和反作用力及组成平衡的二力分别是（）。

A．A

B．B

C．C

D．D

答案

参考答案：A

解析：

根据作用力和反作用力以及二力平衡原理的定义。

单项选择题

关于风湿性疾病临床特点下列哪项说法不妥（）

A.病程多呈慢性，常有反复发作与缓解

B.病变主要累及骨关节及其周围组织如肌腱、滑囊、筋膜等

C.血中常有多种自身抗体出现

D.非甾体消炎药对大多数患者有消炎止肿之功效

E.肾上腺皮质素常有根治功效
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单项选择题

Even though current technologies make the ultimate segmented network impractical, new technologies and products hold the promise of making the concept a reality. Most important of all these new technologies are (66) . The ultimate switched LAN, which is technically possible, now, exhibits the following characteristics:
1. High-speed yet cost-effective switching devices can be implemented on a wide scale, providing dedicated connections for individual users and supporting the aggregate (67) of all networked users.
2. The ability to deploy switching capabilities incrementally into the (68) base. Switching implementations support switching of individual users or groups so that existing users of shared media modules can continue to use the existing equipment until they can justify moving to dedicate switched LAN connections.
3. Support and enhancement of existing routed environments. Switching (69) routint, but rather can be introduced into the network without making any changes to the existing routing equipment or configuration. (70) play a critical role in the integration of switching into existing networks.

A．Routers

B．Devices

C．I/O

D．DSP
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