[shàng xià]
（職務、輩分上的高低） high and low; old and young
the whole nation
舉國上下
All members of the family, old and young, are very pleased.
全家上上下下都很高興。
（從上到下） from top to bottom; up and down
The water tower is fifty metres high.
這個水塔上下有50米。
（從高到低或從低到高） go up and down
With an elevator in the skyscraper, we can easily go up and down.
摩天樓里有電梯，上下很方便。
（程度高低） relative superiority or inferiority
equally matched; about the same
不相上下
hard to tell which is better
難分上下
（用在數量詞后面） about; or so; or thereabouts
about thirty years old; thirty or so
30歲上下