duad

例句：

1. 1. The teacher asked us to work in pairs.
   老师让我们成对工作。
2. 2. They have two children, a boy and a girl.
   他们有两个孩子，一个男孩和一个女孩。
3. 3. The students sat in pairs at the table.
   学生们坐在桌子旁成对坐着。