标签：已知C(石墨)＋O(g)=CO(g)△rHm=.kJ·mol；CO(g)＋(/)O(g)=CO(g)△rHm=–.kJ·mol，则C(石墨)＋(/)O(g)=CO(g)的反应热为?A.kJ/molB.kJ/molC.kJ/molD.kJ/mol