通过垫片材料本体（）的泄漏称为渗透泄漏。
A.毛细现象
B.材质老化
C.机械变形
D.材质龟裂
参考答案：A
Since production has risen ________, the personal income has increased year by year.
A．steadily
B．fortunately
C．particularly
D．variety
危机遮断器超速试验时不动作，其可能原因有哪些？
