污秽地区输电线路外绝缘宜优先选择下列哪些绝缘子？（）
A.钟罩式玻璃绝缘子
B.普通瓷瓶
C.耐污型瓷瓶
D.合成绝缘子
参考答案：C, D
— I'm afraid I couldn't go to your birthday party. I have a test next Monday.
— Oh, _____! You're my best friend and you must be there! [ ]
A. go ahead
B. come on
C. you needn't
D. it doesn't matter
可引起病人脉压增大的疾病是
A．心包积液
B．缩窄性心包炎
C．主动脉瓣关闭不全
D．低血压
E．主动脉瓣狭窄
