第29题: [单项选择]The ignition of the fuel in diesel engine is caused by the () of compression of the air previously admitted into the cylinders. A. vacuum pressure B. specific gravity C. heat D. viscosity 参考答案:C
第30题: [单项选择]于截止阀的优点,表述错误的一项是()。 A. 结构简单,制造和维修比较方便 B. 流体阻力小,开启和关闭时所需力较小 C. 工作行程小,启闭时间短 D. 密封性好,密封面间磨擦力小,寿命较长 参考答案:B