A.揮發(fā)分含量大著火點(diǎn)近,著火迅速,否則著火點(diǎn)就遠(yuǎn) B.煤粉濃度大時(shí)著火點(diǎn)近 C.煤粉越細(xì)則著火點(diǎn)越近,燃盡時(shí)間也短 D.一次風(fēng)速高時(shí)著火點(diǎn)近