If a group of people pair off, they divide into pairs in order to do something, and if you pair them off, you divide them into pairs.

如果一群人pair off，那么就是說(shuō)他們是分成兩人為一組來(lái)做某事的，如果你把他們pair off，那么就是說(shuō)你把他們分成兩兩一組。

兩人一組結(jié)成對(duì);把(一組人)分成幾對(duì)

The students paired off to practise their conversational skills.

學(xué)生們兩人一組進(jìn)行會(huì)話技巧練習(xí)。

After dinner the boys and girls paired off and went to the dance.

會(huì)餐后， 男女青年們成對(duì)成對(duì)地去跳舞。