单项选择题
A.they generate heat
B.they emit hydrogen
C.of the toxic fumes they emit
D.they recharge faster in a well ventilated space
单项选择题 Since electrical burn victims may be in shock，the FIRST medical response is to check for（）
单项选择题 Since accumulations of H2S gas on a ship can be dangerous to personnel，it is important to know that H2S gas is（）.
单项选择题 Severe exposure to chlorine gas can be fatal. Chlorine gas is primarily a（）.