问题
单项选择题
Halon extinguishers used on a class C fire should be directed at the（）.
A.base of the equipment
B.top of the equipment
C.power source
D.source of the fire
答案
参考答案：D
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Halon extinguishers used on a class C fire should be directed at the（）.
A.base of the equipment
B.top of the equipment
C.power source
D.source of the fire
参考答案：D
、
、
，它们的轨道半径之间的关系是
，它们的质量关系是
。则下列说法中正确的是
