[单选] 暗埋的燃气铜管或不锈钢波纹管不应与各种金属和电线相接触；当不可避让时，应用（）隔开。

什么是聚会礼仪？ 什么是安全监察？安全保证和安全监察之间的关系是怎样的？ Which of the following conditions must exist for heat to flow from one object to another?（） The two objects must be in physical contact。 The two objects must be the same size。 There must be an existing temperature differential。 There must be an existing weight differential。 （）shall the amount of compensation from PICC exceed the insured amount of the insured ship. In any case。 In case。 In no case。 In case of。 什么是社交聚会？ 暗埋的燃气铜管或不锈钢波纹管不应与各种金属和电线相接触；当不可避让时，应用（）隔开。