double lay双线铺设doubleadj.双重的；成双的；两倍的v.翻一番；使 ... 加倍n.两倍；双份Double railway track双线铁路double throw contact双向触点Double-foil shield双圆弧罩盖double cutting drill双刃钻double action piston两面作用活塞double acting switch双动开关double-arch tunnel连拱隧道double-current key双流按键double charging bell双料钟double doping method双重掺杂法