the upper three feet of怎么翻译? or后面跟了个to,要怎么理解? support skirts welded directly to the vessel or to reinforcing rings welded to the vessel 是指support skirts要么是直接与vessel焊接在一起,要么是间接地与vessel 焊在一起(support skirts与reinforcing rings焊在一起,而reinforcing rings与vessel 焊接在一起)查看更多