项目工作是指为创造一个独特的产品、服务或结果进行的（）工作
A. 部分
B. 永久性
C. 临时性
D. 多次性
患者，女，63岁。上肢患肢痛一年，实施星状神经节阻滞术。阻滞成功的标志是（）
A. 声音嘶哑
B. 腹式呼吸
C. 患侧出现Horner综合征
D. 呃逆
E. 头面部出汗
A switch that is to be added to the production network has been preconfigured （trunks， VLANs， VTP， and STP） and was tested in your lab. After installing the switch into the network， the entire network went down. What might explain what happened？ （）
A. The new switch happened to be running Cisco Catalyst operating system， while the other network switches were running Cisco IOS Software.
B. The configuration revision of the new switch was higher than the configuration revision of the production VTP domain.
C. The link costs on the new switch are set to a high value， causing all ports on the new switch to go into a forwarding mode and none into blocking mode， thereby causing a spanning-tree loop.
D. The ports connecting to the two switches have been configured incorrectly. One side has the command switchport mode access and the other switchport mode trunk.
适当给以不愉快的体验，使不良行为因躲避此不愉快体验而减少属于正强化。
A. 正确
B. 错误
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