单项选择题
Severe exposure to chlorine gas can be fatal. Chlorine gas is primarily a（）.
A.respiratory irritant B.skin burning agent C.blood poisoning agent D.nerve paralyzing irritant
单项选择题 Separation cloths may be used to（）.
单项选择题 Seasickness is caused by rolling or rocking motions which affect fluids in the（）.
单项选择题 Releasing oil from the sea anchor of a lifeboat may（）.
