PAI-2

排 = to line up, to align

The two-character version for 'to line up, to queue' is:

排队 = pai(2)dui(4) = to queue, to line up

When you stand in a line and others want to overtake you, you can say:

请排队,妤吗? = Qing(3) pai(2)dui(4), hao(3) ma(-)? = Please stand in line, OK?

There is a general trend in the Chinese language to combine two morphemes into words, as this greatly enhances clarity. Many of these combinations of two charactes are bysyllabic new words. However, single-character words retain their usability if they occur in set two-character phrases. An example is:

请排妤! = Qing(3) pai(2) hao(3)! = Please queue well!

In daily conversations, Chinese native speakers would normally not use 排 as a single-morpheme word. But in the combination with 好, this is common usage.

并排 = bing(4)pai(2) = side by side, alongside

两个人并排坐. = Liang(3) ge(4) ren(2) bing(4)pai(2) zuo(4). = Two people sit side by side.