four square 直率的；坦白的
The girl is four square. 这女孩很直率。
on all fours 爬着
The baby was crawling about on all fours. 婴儿那时正在满处爬。
four-lettered words 下流话
These books are full of four-lettered words. 这些书里脏话连篇。
in fours 每组四个
Group together in fours! 每四人一组!
Students are standing in a line，in fours. 学生们每组四人排成队。