three pair三对threenum.三n.三；三个adj.三个的three- winding transformer二三绕组变压器three cold-weather friends岁寒三友three thousand eight hundred(=3800) 三千八百Three dimensional ultrasound三维超声three dimensional constraint三维约束three-dimensional manifold三维流形Three Ponds for Flying Falls飞瀑三潭three hundred and forty nine(=349) 三百四十九three-step circular matrix三步循环矩阵Three Guarantees products.产品实行三包。

1. Its members fell off one by one.
   它的成员一个个地退出了。
2. The children went in two by two.
   孩子们两个两个地进去。