密封电池须经常检查的项目有哪些？
参考答案：
1：端电压
2：连接处有无松动、腐蚀现象
3：电池壳体有无渗漏和变形
4：极柱、安全阀周围是否有酸雾酸液逸出
Our senior high school has _____ students as my junior high school.
A．as twice
B．twice many
C．twice many as
D．twice as many
