单选题
1分
For a fire to begin there must be present a combustible material, oxygen, or air to ___ combustion, ...
For a fire to begin there must be present a combustible material, oxygen, or air to ___ combustion, and a source of heat at a temperature high enough to start the combustion.
参考答案: B
参考解析: 火灾要发生,必须要有可燃物质、氧气或空气来支持燃烧,以及使之开始燃烧的高温热源。