four square 直率的；坦白的

The girl is four square. 這女孩很直率。

on all fours 爬著

The baby was crawling about on all fours. 嬰兒那時正在滿處爬。

four-lettered words 下流話

These books are full of four-lettered words. 這些書里臟話連篇。

in fours 每組四個

Group together in fours! 每四人一組!

Students are standing in a line，in fours. 學生們每組四人排成隊。