单项选择题
On a hydrocarbon flammability chart the line which extends from 0% to 21.8% oxygen，lying tangent to the flammability range，is called the（）.
A.minimum oxygen content line
B.critical displacement line
C.critical dilution line
D.upper threshold limit
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相关考题
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单项选择题
If，during helicopter refueling operations，fuel is spilled on clothing，the person should first（）.
A.see the medic immediately
B.spray himself with foam or CO2
C.complete his task and then see the medic
D.remove the clothing and wash -
单项选择题
Each part of the fire-main system located on an exposed deck must be（）.
A.protected against freezing
B.locked to prevent theft
C.numbered sequentially
D.pressurized at all times -
单项选择题
Each hose in the fuel transfer system for helicopter refueling must meet the standards of the（）.
A.Federal Aviation Administration
B.Corps of Engineers
C.National Fire Protection Association
D.National Transportation Safety Board
