单项选择题
After putting on a self-contained breathing apparatus，you open the air supply and hear a continuous ringing of a bell. What does this mean? （）
A.The unit is working properly
B.The face mask is not sealed properly
C.The air bottle needs to be refilled
D.The air supply hose has a leak
点击查看答案&解析
相关考题
-
单项选择题
According to the Chemical Data Guide，epichlorohydrin is a(n)（）.
A.corrosive
B.class B poison
C.oxidizer
D.explosive -
单项选择题
A space should be ventilated when（）.
A.The cargo's temperature is colder than the dew point of the air in the space
B.The cargo's temperature is warmer than the dew point of the air in the space
C.The dew point of the air in the space is lower than the dew point of the outside air
D.All of the above -
单项选择题
（）is the most liable to spontaneous combustion.
A.Cement
B.Chinaware
C.Fish meal
D.Steel products
