【单选题】All naturally occurring forest fires are caused by lightning strikes.
【简答题】A.Criminals who set the fires on purpose. B.Natural lightning strikes. C.Sparks from vehicles. D.Carelessly discarded cigarettes.
【简答题】( )失去整体稳定时,该结构件应判为不合格。 A.重要结构件 B.一般结构件 C.结构件 D.齿轮表面
【判断题】碱性焊条一般用于低碳钢重要结构件中,因强度较酸性焊条高。( )
【单选题】下列关于恶性肿瘤分期的描述不正确的是( )