97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区 狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

單項(xiàng)選擇題

One disadvantage of using regular dry chemical (sodium bicarbonate) in firefighting is that().

A.it can break down under high heat and emit noxious fumes
B.it will decompose under prolonged storage and lose its effectiveness
C.fire has been known to flash back over the surface of an oil fire
D.it is ineffective in fighting fires in high-voltage electrical equipment

微信掃碼免費(fèi)搜題