压力表属于（）安全附件。
A、显示和显示控制类
B、超压泄放类
C、紧急切断类
D、安全联锁类
参考答案：A
Although metals________widely in qualities such as strength and hardness, they all have certain qualities
in________.[ ]
A. vary; general
B. differ; common
C. react; particular
D. refer; detail
脚手架的防电要求（）：
A.包扎隔绝
B.接地处理
C.接零
