单项选择题
Storage batteries should be charged in a well ventilated area because（）.
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 One of the principal dangers inherent in liquefied petroleum gas is（）.
单项选择题 Name one major advantage of transporting gas under refrigeration.（）
单项选择题 LFG tank and pipeline maintenance should include（）.
