第18题: [单项选择]A mixture of 45%cetane and 55% alpha-methyl-naphthalene is found to have the same ignition delay as a sample of diesel oil √The sample can be described as having a/an() A. cetane number of 55 B. cetane number of 45 C. octane number of 55 D. octane number of 45 参考答案:B