下列不属于常见修正性维护操作是()
A. 表面非正常突起的修整
B. 更换或补充防腐剂
C. 补充惰性保护气体
D. 更换密封垫
消防专用电话、电话插孔、带电话插孔的手动报警按钮宜安装在明显、便于操作的位置;当在墙面上安装时,其底边距地(楼)面高度宜为()m。
A. 1.3~1.5
B. 1.3~1.6
C. 1.1~1.5
D. 1.2~1.5
It was well known that Thomas Edison()the electric lamp.
A. invented
B. discovered
C. found
D. developed