汇线槽在自控仪表的安装中占有特殊的位置，多采用（）的连接方式。
A．焊接
B．法兰
C．螺栓
D．卡套式
参考答案：A, C
治疗癃闭实证的主穴为
A．三阴交
B．中极
C．肾俞
D．膀胱俞
E．秩边、阴陵泉
A rectangular circuit board is designed to have width叫inches, perimeter p inches, and area k square inches. Which of the following equations must be true ？（）
A．ω2+pω+k=0
B．ω2-pw4+2k=0
C．2ω+pw+2k=0
D．2ω-pω-2k=0
E．22ω-pw+2k=0
