n.潛艇；替代品
vi.替代
vt.轉(zhuǎn)包合同
The nuclear-powered submarine can overrun any other sub. 核動(dòng)力潛艇能比其他任何潛艇駛得快。
用作不及物動(dòng)詞 (vi.)I had to sub for the referee, who was sick. 裁判病了，我得代為裁判。
Clive Walker came on as a sub and starred. 克里夫-沃克替補(bǔ)上場，大放異彩。
