1.one in a thousand 千里挑一,稀有的,杰出的
例句：So, what autism is a disorder that strikes about one in a thousand people, mostly boys.
孤独症的发病率约为千分之一，病患多是男孩。
2.once in a while 偶尔，间或
例句：He comes to our room for a chat every once in a while.
他偶尔来我们房中闲谈。
3.once more 再一次
例句：So on this solemn day, at this sacred hour, once more we pause.
在这庄严的日子，在这个神圣的时刻，让我们再一次停顿一下。
4.one by one 一个一个地,依次地
例句：We always went one one out the back.
我们总是一个一个地从后门出去。
5.one after another 一个接一个的（地），接连
例句：One another stood up and went out.
人们一个一个地站起来，走了出去。
6.one another 彼此，互相
例句：The casks rolling about on the desk knocked against one another.
几只滚动在工作台上的木桶互相碰撞。