单项选择题
To determine the pressure and temperature limitations under which LFG is required to be transported on a barge，you should look at the（）.
A.Certificate of Inspection B.loading order C.rules and regulations for tankers D.tankerman's document
单项选择题 The weight of liquefied petroleum gas vapors as compared to air is（）.
单项选择题 The vapor pressure of a substance（）.
单项选择题 The vapor pressure of a gas is the pressure necessary to keep it in a(n)（）.
