两个cover翻成什么好? this specification covers the requirements for the fabrication and testing of seamless mechanically bonded bimetallic tubes for urea service with an outer tube of stainless steel and an inner tube of zirconium. 本技术规范覆盖了用于尿素装置的机械胀接无缝双金属管(不锈钢外管、锆材内管)的制造与测试要求。查看更多